We walked out into a bed of dead corals at sunset, meaning to walk to a point where the corals were alive. The tide was coming in, and we had little time. But I got distracted. There were tentacles waving below the surface of the water. When I looked closer I saw a strange starfish, climbing up a submerged stone using all five tentacles around its round body.
Once I knew what to look for I could see them everywhere. They would usually have a bolt hole where they would retreat to hide or feed. Feeding consisted of pushing a couple of tentacles out of its cave and agitating the water around it. Presumably this enabled them to catch tiny organisms floating in the water. It looked like a child stuffing her mouth while out picking blueberries.