I've tentatively identified this fossil as a lambeoceras. It's from an Ordovician limestone of the Red River formation. Unfortunately, I can't find much in the way of information on the lambeoceras! Anything in terms of environment, diet etc would be greatly appreciated.

The fossil in question (quite a large bugger, I might add): [img=http://img120.imageshack.us/img120/5576/uplambiodk6.th.jpg] (http://img120.imageshack.us/my.php?image=uplambiodk6.jpg)

:welcome: davort,

Nice fossil, it had me confused for a while, seemed like the concave part of the septa were going backwards, obviously a artifact of the cutting process for the tile.

The only info I could find is on Wikipedia (http://en.wikipedia.org/wiki/Lambeoceras).

:welcome: to TONMO!