# Mars rock "sushi" ... what is it? **URL:** \ **Category:** Factual Questions\ **Created:** [February 12, 2004, 5:30pm UTC](https://boards.straightdope.com/t/mars-rock-sushi-what-is-it/228884 "2004-02-12T17:30:33Z")\ **Posts on this page:** 16\ **Page:** 1
**Author:** ![toadspittle](https://avatars.discourse-cdn.com/v4/letter/t/c0e974/32.png) [@toadspittle](https://boards.straightdope.com/u/toadspittle)\ **Post date:** [February 12, 2004, 5:30pm UTC](https://boards.straightdope.com/t/mars-rock-sushi-what-is-it/228884/1 "2004-02-12T17:30:33Z")
So the Spirit rover photographed a cool rock, which NASA has dubbed “Sushi” (its neighbor is called “sashimi”): [![](https://mars.nasa.gov/mer/gallery/press/spirit/20040119a/P2543_Sol14_L456-A16R1.jpg) ](https://mars.nasa.gov/mer/gallery/press/spirit/20040119a/P2543_Sol14_L456-A16R1.jpg) What is this thing? Geode? Weird, extremely rectilinear volcanic bubble? Trick of the light? ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [February 12, 2004, 5:44pm UTC](https://boards.straightdope.com/t/mars-rock-sushi-what-is-it/228884/2 "2004-02-12T17:44:55Z")
Ummm… it’s a rock. The surface texture looks like wind/dust erosion - almost like sand dunes where slight irregularities are self-amplifying. The difference in colours looks like adhesion of light-coloured dust to a dark-coloured surface, exposed on the edge facing the prevailing wind - the pattern of surface colour on the smaller surrounding pieces is also significant. IANAGeologist though, so prepare to see my face turn red. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [February 12, 2004, 5:48pm UTC](https://boards.straightdope.com/t/mars-rock-sushi-what-is-it/228884/3 "2004-02-12T17:48:21Z")
Oops; one more detail I only just noticed - see the slightly darkened ring of surface soil forming a ‘halo’ around the rock, starting at (what I’m now fairly sure is) the windward side. (prevailing wind emanating from the upper right corner of the frame, I’d say). ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [February 12, 2004, 5:54pm UTC](https://boards.straightdope.com/t/mars-rock-sushi-what-is-it/228884/4 "2004-02-12T17:54:03Z")
Aaaaaand I’ve been describing the wrong rock - you mean the one that is at the far right of the frame (invisible until I opened the window to full screen - I have image resizing switched off). I have no idea what that is - best (but worthless) guess is that it is a void left by a bubble of gas in cooling volcanic rock - the shape is odd though, but if the bubble was elongated and the rock continued to deform as it cooled, it could easily end up with a non-circular cross-section. The edges of that rock look a little ‘bubbly’ too. ---
**Author:** ![jjimm](https://avatars.discourse-cdn.com/v4/letter/j/ba8739/32.png) [@jjimm](https://boards.straightdope.com/u/jjimm)\ **Post date:** [February 12, 2004, 6:03pm UTC](https://boards.straightdope.com/t/mars-rock-sushi-what-is-it/228884/5 "2004-02-12T18:03:22Z")
> [@](#): > > prepare to see my face turn red You a clairvoyant? ---
**Author:** ![Phlosphr](https://avatars.discourse-cdn.com/v4/letter/p/c68b51/32.png) [@Phlosphr](https://boards.straightdope.com/u/Phlosphr)\ **Post date:** [February 12, 2004, 6:42pm UTC](https://boards.straightdope.com/t/mars-rock-sushi-what-is-it/228884/6 "2004-02-12T18:42:53Z")
Looks like a fragment of a meteor hit…see all the pock marks…Hmmm. I do know one thing, you can bet spirit took a lighted shot of the inside of that thing. 🙂 Can’t wait for them to discover something that looks “_unnatural_” 🙂 ---
**Author:** ![Cervaise](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cervaise/32/16693_2.png) [@Cervaise](https://boards.straightdope.com/u/Cervaise)\ **Post date:** [February 12, 2004, 6:48pm UTC](https://boards.straightdope.com/t/mars-rock-sushi-what-is-it/228884/7 "2004-02-12T18:48:30Z")
> [@toadspittle](#): > > What is this thing? Looks to me like the dropping of an Elder God. When Cthulhu’s bunghole slams shut, it really slams shut. ---
**Author:** ![Yossarian](https://avatars.discourse-cdn.com/v4/letter/y/9de0a6/32.png) [@Yossarian](https://boards.straightdope.com/u/Yossarian)\ **Post date:** [February 12, 2004, 6:50pm UTC](https://boards.straightdope.com/t/mars-rock-sushi-what-is-it/228884/8 "2004-02-12T18:50:19Z")
Looks like a typical ventifact to me. (IAA Geologist, but not a geomorphologist.) ---
**Author:** ![Frank\_2](https://avatars.discourse-cdn.com/v4/letter/f/8c91f0/32.png) [@Frank\_2](https://boards.straightdope.com/u/Frank_2)\ **Post date:** [February 12, 2004, 9:19pm UTC](https://boards.straightdope.com/t/mars-rock-sushi-what-is-it/228884/9 "2004-02-12T21:19:48Z")
Looks like a nice piece of yellowtail with some mackerel on the side. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [February 12, 2004, 9:33pm UTC](https://boards.straightdope.com/t/mars-rock-sushi-what-is-it/228884/10 "2004-02-12T21:33:02Z")
> [@jjimm](#): > > You a clairvoyant? Nope, I just do stupid things with more or less predictable frequency. ---
**Author:** ![sunfish](https://avatars.discourse-cdn.com/v4/letter/s/96bed5/32.png) [@sunfish](https://boards.straightdope.com/u/sunfish)\ **Post date:** [February 13, 2004, 2:26am UTC](https://boards.straightdope.com/t/mars-rock-sushi-what-is-it/228884/11 "2004-02-13T02:26:23Z")
Given that holes are also visible in the cross-section of the smaller chunk near the bottom of the photo… maybe vesicular basalt that’s been modified by wind erosion? See, this is why a rover, as cool as it is, will never be as good as a human. A geologist on the scene could have figured it out with a simple whack of with his/her hammer. 😉 ---
**Author:** ![pcroughn](https://avatars.discourse-cdn.com/v4/letter/p/977dab/32.png) [@pcroughn](https://boards.straightdope.com/u/pcroughn)\ **Post date:** [February 13, 2004, 5:16am UTC](https://boards.straightdope.com/t/mars-rock-sushi-what-is-it/228884/12 "2004-02-13T05:16:52Z")
Thank you Mr. Wizard(s), but as anyone can plainly see it’s a hunk of that dehydrated chicken found in Cup-O-Noodles. Jeez, you guys always go right for the science! ---
**Author:** ![Yossarian](https://avatars.discourse-cdn.com/v4/letter/y/9de0a6/32.png) [@Yossarian](https://boards.straightdope.com/u/Yossarian)\ **Post date:** [February 13, 2004, 1:08pm UTC](https://boards.straightdope.com/t/mars-rock-sushi-what-is-it/228884/13 "2004-02-13T13:08:40Z")
> [@sunfish](#): > > …that’s been modified by wind erosion? = a **ventifact**. It is most likely a clast derived from basalt, but I’d wager that the basalt was not vesicular. > [@](#): > > See, this is why a rover, as cool as it is, will never be as good as a human. A geologist on the scene could have figured it out with a simple whack of with his/her hammer. 😉 Agreed 100%! ---
**Author:** ![Keweenaw](https://avatars.discourse-cdn.com/v4/letter/k/da6949/32.png) [@Keweenaw](https://boards.straightdope.com/u/Keweenaw)\ **Post date:** [February 13, 2004, 1:44pm UTC](https://boards.straightdope.com/t/mars-rock-sushi-what-is-it/228884/14 "2004-02-13T13:44:59Z")
Interesting slot rock interpretation, and a few different pics [http://enterprisemission.com/images/Spirit/Slot-rock.jpg](http://enterprisemission.com/images/Spirit/Slot-rock.jpg) ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [February 13, 2004, 2:18pm UTC](https://boards.straightdope.com/t/mars-rock-sushi-what-is-it/228884/15 "2004-02-13T14:18:39Z")
> [@Keweenaw](#): > > Interesting slot rock interpretation, and a few different pics > > [http://enterprisemission.com/images/Spirit/Slot-rock.jpg](http://enterprisemission.com/images/Spirit/Slot-rock.jpg) [SeeThuArt]It’s the massive tiny garage where the giant aliens park their miniature Space Shuttles.[/SeeThruArt] ---
**Author:** ![Cervaise](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cervaise/32/16693_2.png) [@Cervaise](https://boards.straightdope.com/u/Cervaise)\ **Post date:** [February 13, 2004, 4:27pm UTC](https://boards.straightdope.com/t/mars-rock-sushi-what-is-it/228884/16 "2004-02-13T16:27:31Z")
> [@Keweenaw](#): > > [http://enterprisemission.com/images/Spirit/Slot-rock.jpg](http://enterprisemission.com/images/Spirit/Slot-rock.jpg) Where are the space raccoons?