I see hermit crabs out on the reef and especially in the shallows all the time. However today I spotted one that had a very pretty but strange looking shell , looking down from the surface:

I dove down a couple times hoping to catch it when the light was good and the surge not clouding the water. I touched one of the anemones on it and it scurried under a rock. I surfaced for air and discovered a second one very similar in size and color up on the side of the cavern:

Cropped in closer for detail:

This second one dropped down and joined the first under the rock. I could see both of them but decided to swim away and come back later and hopefully catch them out again. I cam back but couldn't find either of them. I don't recall ever seeing one of these before and it was interesting to find a pair of them. I have no idea what the shells they occupied looked like as they were covered with these anemones.