yeah its a cowrie snail, it looks like either Cypraea tigris, the tiger cowrie, which is known to feed on algae, but also on fish - and mussel/clam meat.
it also looks like Cyprae histrio, which i dont have any info on and am just going off of a pic of the shell
good luck, most cowries prey on coral/in th ewild, but there are a few that are algae eaters. keep your eye on it
jon