Collected this in Plano, Texas when I was a kid back in the early 1980s. Construction equipment had dug up some limestone and piled it next to the road. There were a lot of broken Inoceramus shells, this was the only intact fossil that I found. Looks different than Inoceramus. Does anyone know what species this would be. I have never found another like it. Measures 2 3/8 inches across.