ID on Elegance hitchhiker plz

[asylumdown]

Noticed this tonight after the elegance closed up for the evening. I've never seen anything like it, this little guys appears to have burrowed right in to the skeleton of the elegance where the tissue meets the skeleton. There's an empty hole nearby that looks like a previous burrow. I took some video of him moving his tiny little claws (they have little pincers on the end of them) but don't know how to share it here unfortunately.





Not sure if he's dangerous. That white plate on his head completely plugs the hole when he retracts, but when he was in the tank I saw him poking little legs out along with the pincers. Doesn't look like any crab I've ever seen before. During the day he'd be totally covered by the mantle of the coral