Mainly because they provide so many different places for animals to live and hide. Creatures here cling to cliffs, climb atop rocks, dangle from ledges and squeeze inside crevices.
Vertical cliffs support jellies and other animals that can hold on tight.
Rocky ledges provide perfect perches for feather stars. Crevices create hiding places for squat lobsters and other animals. Large rocks shelter fishes. Animals, like this vase sponge, offer a safe haven for brittle stars .