Mystery 'Fossil'... cool picture !
 

Quote from web site.

Update: People have been telling me that it is a Bismuth crystal and that it is grown in a lab. It is very common and grows very rapid. By far the most interesting crystal growth I've ever seen. Almost alien! --Gabriel

I bought this thing at a crystal and gem store because I've never seen anything like it. What is it? Well I asked two different people there and one said that it was silicone carbide and that it was grown in a lab. Another person also said that it was silicone carbide and that it was a byproduct of some process in making micro-chips and it naturally grew that way. Well ok…never heard of it or seen anything grow like this before. I checked out the rest of the pieces they had and out of about 8 left they all were somewhat different but they all had the same geometry.

http://www.coasttocoastam.com/gen/pa...ml?theme=light

There's a nice photo of a bismuth crystal on Wikipedia as well: http://en.wikipedia.org/wiki/Image:B...stal_macro.jpg

It is bismuth, but unfortunately it is manufactured in a lab. Naturally occuring bismuth extremely rarely is pure enough to form crystals like that. They are however really cool looking none the less.