Ammonites, near Fort Worth, Texas

Not far from my mother's house in Fort Worth, a creek has dug a wide gully down through about ten feet of chalky sediment. Walking by, last week, we happened to notice that some of the rocks had shapes, and over a few visits, gathered a number of these fossils. I'm not at all sure of my identifications, and would welcome corrections, but the ones above seem to be ammonites, ancient versions of the nautilus, squidlike creatures that lived in curvy shells. Those below are various snails, aka gastropods. Below left are a kind of echinoderm, sort of fat versions of sand dollars, perhaps the ones known locally as "Texas stars" or "Texas hearts." The twisty, filamentous ones below right are mysterious to me—worms? seaweed?

Gastropod fossils, near Fort Worth, Texas

Echinoderm fossils, near Fort Worth, Texas, also called Texas stars

Fossils, found near Fort Worth, TX