I was watching an old edition of QI, a quiz show on the BBC here in the UK that prides itself on extreme accuracy.
During the course of one question, it was mentioned that quartz is stronger than a shark’s tooth. We were then told that 20% of the Earth’s crust is quartz which is the remains of animals like sponges. True?
And on the subject of sponges, if a couple of different species of sponge were shredded using a sieve for example and the resulting goop drained into a tank of salt water, eventually the individual sponges would separate from each other and the whole individual sponges would reform. True?
False. Quartz is silicon and oxygen, SiO[sub]2[/sub], an igneous rock that comes from volcanoes. Sponges, being animals, would contain minerals like carbon and calcium. This notion is actually sillier than oil coming from dinosaurs.
Sponges may have internal structures composed of spicular opaline silica or, less commonly, calcium carbonate. These spicules may accumulate in layered deposits but I’d characterize them as more “cherty” than quartz-like and they certainly don’t begin to approximate 20% of the Earth’s crust.
I have seen this episode of QI several times, and listened intently to what was said about
sponges and “quartz” … Steven Fry did not state that 20% of the earths crust originated from sponges, or that all quartz originated from sponges … Fry talked about chert / chalcedony / flint (which are all the same chemical as quartz : SiO2) originating from sponges. He did not even state that all flint originated from sponges. What was said was confusing and rather muddled (so no wonder so many of you misunderstood what was being said) … It seems a reasonable assumption that flint / cert / chalcedony found in limestone areas does indeed originate from the silcon from sponges, just as the limestone there originates from the calcium carbonate (CaCO3) from shells and bones
Its perhaps suprising that Fry did not mention that SiO2 is glass is quartz is flint is chert is chalcedony is chrysoprase is jasper is amethyst (etc) , as all these things are the different forms of the same chemical compound Silicon Dioxide … marvelous stuff
Absolutely not true. Sponges do have a pretty good ability to regenerate - cut one in half and you wind up with two small sponges that would grow independently from them on. If you shredded them, though, you’d just have a whole mess of dead sponge.
I have actually seen the experiment done on some nature show. They’re not being “shredded”, exactly, just reduced to individual - but intact - cells. Those cells do reassemble over the next few days and weeks. I haven’t done it firsthand, but I believe the source I saw was quite reliable.
I dunno about that. If you’re having a QI marathon one of these days, then “spot the horrendous mistake” is usually good for a drinking game. I have a feeling it’s getting worse as the seasons go on, too.
quartz is harder than a shark’s tooth. almost 99% of the earth’s crust is composed of various silicates but quartz as a free and distinct mineral is not likely to account for 20% of the crust (i could be wrong though, 20% seems close if you consider the quartz-rich continental granitic masses.)
majority of the crust (and even the mantle) is composed of heavy and dark iron- and magnesium-rich silicates such as basalts and gabbro, peridotites and dunites. these rocks are low in quartz content. it is the continental masses that float over these dark rocks that are (light) granitic and contain a lot of quartz.
having said that, sedimentary remains of animals form only a very thin carapace over the surface of the crust (and not the entire surface, just a small portion.)
yes, poriferas display the best regenerative abilities in the animal kingdom. your word-for-word account of a sponge pushed through a sieve and coming out whole again is straight out of the guiness book.
