Looks like a vermented snail. They are generally considered pests in the reefing hobby. In many cases bumble bee snails will eat them, but you can also do manual removal. You can use bone clippers to remove them manually if it is bothering your coral. (Digging into the flesh or releasing mucus) Make sure to do your research.
Yup Vermatid. Common aquarium pest. They will harass your corals. Bumble Bee snails will control them, but not eradicate them. If you try to remove them they can go down to the base of their tube and try to escape so you have to be thorough with removal. Can also super glue their tubes shut.
Had a major infestation of these on my last tank to the point where I had to pull out all of the rock, remove as many as I could, then start a control routine from scratch. The Bumble Bee snails helped a lot.