Maze coral squatters

[chester]

I've just added a new piece of maze coral with what I thought were a few uninhabited holes in(about 1/8th inch across) but now apon closer inspection they seem to house somw sort of small crab which can bolt down the hole! any ideas what these might be?

 

[Jawbone]

It could be a Filter feeding hermit crabs I have one on one of my rocks

here is a close up pic of one of mine.