No idea what it is... but one can hope it's a cephy fossil! :bugout:

http://i249.photobucket.com/albums/gg231/thehippydaledo/IMG_1127.jpg
http://i249.photobucket.com/albums/gg231/thehippydaledo/IMG_1131.jpg
http://i249.photobucket.com/albums/gg231/thehippydaledo/IMG_1130.jpg
http://i249.photobucket.com/albums/gg231/thehippydaledo/IMG_1118.jpg

Looking forward to finding out what it is if any of you fossil folks can help out. It's a little bigger than a golf ball. Looks like one quarter of an ammonite but I don't know. I hope the pictures show the details well enough.
The place where I work has a lot of rock on the walkways and I've been finding a lot of fossilized bi-valve shells so I've been looking very carefully lately and this was the absolute jewel so far. I actually found a completely intact bi-valve today also.

That looks like a section of Mortoniceras, an Early Cretaceous ammonite. 8-)

I'll see if I can get a better ID.

Awesome. You just made my day. I knew I wasn't totally crazy!

When we lived in Fort Worth we dug a lot of ammonites from our back yard. I think Erich has them now. Someone at the Smithsonian dated and identified them for us after we moved to Virginia. Some of them were fragments, but some were intact and quite large, a foot or more in diameter.....

I live right by the Fossil Creek area and I'm really tempted to go scavenging along the creek bed sometime. The huge ammonite on the area sign makes me wonder just how prominent they are around here. I helped a friend dig up an old septic tank out by Texas Motor Speedway a while back and found some bi-valves while doing so. I wish I'd sifted through the excavated earth a lot more now. I dug up a hole for a pond in my backyard and it was mostly clay so I don't think I'll find anything here. At least not without some serious labor.

All the rock I've been going through at work was bought and brought in from somewhere else. I had just assumed that since there were obvious signs of ancient marine life I would eventually find something besides bi-valves. I found another piece that had an imprint of something similar to this piece, but it was much smaller so I left it.