The Florida rock snail is part of the murex family. This is only the second rock snail shell I’ve collected, so they are not seen regularly by me, although they are a fairly common mollusk found all around the coast of Florida.
They tend to live on jetties, where they have rocks to cling to. And this shell was found on the shore near the jetty at Ponce Inlet. It makes sense that it would have washed up there.

The Florida Rock Snail Shell is Orange Inside

My shell shown here is a little less than 2 inches long. My go-to reference book claims that their max length is 3 inches. When I picked it up and saw the orange inside I knew what it was. Not all rock snails (Stramonita haemastoma) have to be orange inside, but the two I have collected do have this coloring.

Rock Snail shell comparison to book image

Here I have taken a photo of my shell sitting on the page where the writers have shown a photo of the same type of shell. You can see they look very similar.
The shell is gray and brown and not super colorful. Mine had some barnacles which chipped off when I cleaned it.

To read more about the Florida Rock Snail and see a photo of the egg casings, go to the Bailey-Matthews National Shell Museum site.