Panama city beach creature identification?
A few days ago I was walking along the shore of the gulf of Mexico in panama city and I came across something floating in the water. I picked it up and thought it was some sort of shell, it was brown with a strange pattern on it and had a round shape with a hole on the bottom. after holding it for a while i realized there was something living inside of it, I would describe what I saw of it as a strange snail but it's shell doesn't look like one. does anyone know what the heck this thing is?