Certainly looks possible to me. It could be an endocast, that is, a mold of the shape of the shell formed by sediment contained within the shell after the original shell has disappeared. Here are photos of other snail fossils from Texas.
To find out more, you would have to figure out the exact geological formation where the fossil was discovered. From this geological map,it looks like the San Antonio area in near the Cretaceous-Tertiary boundary in Texas.
Snails are very common fossils. In Minneapolis, I used to collect them on the limestone bluffs of the Mississippi. Each rock Iād pick up was chock full of snails and other marine fossils!
If your daughter is interested in fossil collecting and geology, you might get her the Roadside Geology of Texasā as I recall, it talks about some good fossil-hunting locations.