Hey all, thought I would share some photos with you and get a few questions out. A while back I found a peice of gravel in my driveway that comes from a mine in my area. One of the few underground limestone mines in Iowa, Ames Mine (Martin-Marietta). See the topic tags for the type of limestone it most likely is. Anyhow, most of it is pretty devoid of any fossils, its a gray (mostly oolitic) limestone, some of it dark gray, some of it light. This peice of gravel popped out of the mix, its as far as I can tell a aquatic snail. The outside was beat up so I decided to take it to a grinder a