One of the better known theories of science is that a giant rock slammed into earth 65 million years ago killing off all the T-rexes (and most everything else). The key part of the puzzle leading to the discovery was finding an unusually high spike of iridium metal on the sediment layer dating to this time period; not just near the impact but everywhere on earth.

The relevance here is that iridium is so rare that even a slight bump in the expected distribution curve is cause for suspicion that it's of an extraterrestrial origin. Now, we're not talking about a neat silvery layer... this is all in the parts per million and is precisely the reason why that meteorite, which was likely made up mostly of iron and nickel, would not have registered had it not been for that measurably higher trace amount of Ir: the iron and nickel being so common here on earth that it gets lost in the background noise.

This piece of iridium came not from outer space but rather deep within our earth's mantle where at some point it concentrated due to its super-high density and a volcano coughed it up to the surface.

Comes sealed in Lucite acrylic of optical clarity and makes for one mind-blowing desk ornament!