No, the thing in the 2nd pic moves around quite a bit.
At first, I thought it was some worms moving in and out of a hole in the rock, but then it moved a little bit, and I saw the outline of it.
It looks like a tiny tiny crab of some sorts (Maybe the size of a pencil eraser, or just a BIT bigger than that)
The squarish shape in the dead center of the picture is his body.
Just above and to the left of that, you can see 3 of the legs.. They are kinda flat shaped, not like Hermit crab legs at all..
Also, in the 1st picture, every 3 or 4 seconds, these things complete a 'cycle', in which they come out of the rock, open up into a fan shape like in the picture, twirl around, and go back into the rock.
I estimate that there are about 50 or so in total on all of the rock I got.