Hermit Crab uses rock to protect itself
As one of these Hermit Crabs appears to be eating, it comes up behind another Hermit with bad intentions. You can see that the Hermit Crab being attacked knew something was up. Watch as it clutches a rock tightly, and at the last minute, brought it up into his shell, protecting himself. In the end, the blue hermit finally moved on. Credit to 'CynthiaB'.