How about… just a proton? 
Quick Googling seems to indicate that neutron stars spin so fast, they tend to go flatter at the poles than, say, The Sun. If surface-smoothness is a separate measure from oblateness, then neutron stars may well be the smoothness champs.
Nah. It has 3 quarks so pretty sure it’s a triangle.
For comparison, the Earth’s diameter is 42 km larger measured across the equator compared to measuring through the poles. Scaled to the size of a volleyball (8 inches), the difference would be 0.7 mm, between 4 and 40 times the width of a human hair, depending on whose hair you’re using. At that scale, Mt. Everest would be 0.14 mm high, which is in the range of a human hair width.
According to this paper, there is no oblateness in a non-rotating neutron star so I still contend it is the winner.
Show me an actual non-rotating neutron star.
Right there
(points to non-rotating neutron star)
Does that count as “observed in nature”?
Non-rotating neutron star wins in a walkover, but we would have to actually observe one for it to satisfy the folks at Guinness.
Here’s something I should have known decades ago but somehow missed.
The Who’s album Tommy contains a cover song.
Obviously not. But why has nobody has pointed out that soap bubbles also aren’t observed in nature?
Well, there’s sea foam.
Soap bubbles are kind of difficult to measure for roundness. Not impossible, but pretty challenging.
Depends on what you mean by “roundest observed in nature”. We’ve observed oodles of stars in nature, and it’s almost certain that many of them are rounder than the Sun. But for any star other than the Sun, it’s really hard to directly measure just how round they are.
Then again, for a quiet, main-sequence star, the primary thing that would make it not-round is rotation, and we can measure the rotation rates of other stars fairly well. There surely must be some other star whose known mass and rotation rate would imply that it would be rounder than the Sun.
I’m pretty sure it’s legitimate to take it as “the greatest degree of roundness we can directly observe in nature”.
The tale of the movie The Primevals is amazing. Talk about development hell.
The project’s origins date to the 1920s with the plot based on ideas from some Edgar Rice Burroughs’ stories.
In the 1960s, stop-motion expert David Allen and friends tried to get funding based on the old idea. They filmed a promo reel. Eventually Hammer Films was interested but they decided to do another project instead.
In the 1970s and 80s Allen tried again to get it made. An outline lead to a script, backers were found and lost. But it did make the cover of SF fan magazine Cinefantastique, It was advertised as an upcoming film, but it didn’t happen.
In the late 80s it was re-launched. Main live-action photography took place in Romania in 1994. But the stop-motion stuff stalled out and things fizzled. Allen tried to keep the film going but died in 1999. His materials ended up with his friend Chris Endicott.
Endicott and long-term backer/producer Charles Band launched an Indiegogo fundraiser in 2018. Enough money was raised to complete it. It debuted in Toronto in June 2023.
One of the actors was Robert Cornthwaite who died in 2006. He would have to have lived to 106 to see the film’s release.
For a film that basically took a century to make, it’s only 5.7 on IMDb. OTOH, all 4 critics reviews at RT are positive and it has a fan rating of 71%.
Over 3000 ocean-going ships are registered in Mongolia and thus fly the Mongolian flag.
Mongolia is land-locked and is hundreds of miles from any navigable ocean water.
Continuing on the topic of ships - the US has exactly ONE US-flagged ocean-going cruise ship (“Pride of America” which does Hawaiian cruises). Any other US-flagged passenger ships are designed for rivers and relative calm coastlines.
Then why use their flag?
Possibly because
“Inspections are quick and regulations are few. Just sign on the line and go find you a crew.”
–Steve Forbert, “The Oil Song”
I’ve brought this up on the Dope Board before/ I tried to give it its New England Premiere a year ago, but they pulled the rights on me. I obtained a copy when the fim came out, and I love it.
There are other films with similarly long histories. Richard Wright’s The Thief and the Cobbler never did have a proper release for the canonical version, but you can watch it on YouTube.
Here are some other works long delayed:
I own a copy of Mad God