Fossil tooth of some type?

[Appleseed21]

Hey all,
I was searching in a central Illinois creek for native artifacts and found what I think is a fossil tooth.
I have found other very old rocks and geodes in the same creek, so there are a wide range of possibilities as far as what it could be.
Any help on what animal it could be from would help. Thanks!

[Hoss]

It looks like Horn Coral to me

http://forums.arrowheads.com/forum/general-discussion-gc5/fossils-paleontology-old-bones-gc30/90581-ohio-horn-corals

[orari]

Good job Hoss!!!  My college minor is in geology, and that is definitely the bottom portion of a piece of Rugosa coral---same as horn coral---as you say.  They go back in time as far as the Ordovician Period---about 500,000,000 years ago.

[Appleseed21]

Wow! Thank you guys for the info!