So very purple

At mid-tide level, near Kwomais Pont, the cracks in the rocks are stuffed with starfish.

All the ones we saw, on this visit, were mid-sized, 6 to 8 inches across. At maturity, they can be up to 20 inches, and 20 years old.

Unusually regular "flower petal" pattern at the top of this one. The neighbour is a contortionist, showing off the underside of one of the arms.

What always intrigues me is how, with such solid, unmovable flesh, they manage to squeeze themselves into impasssible cracks between rocks.

Or why, being so tough-skinned, so un-cuddly, they pile up in such affectionate poses.

The skin of starfish is covered in hard conical projections or tubercles which extend into spines in some species. The 'skin' or dermis is also impregnated with hard stony plates called ossicles. These are made principally of calcium carbonate with some magnesium carbonate and other
salts. ...
 The marginal plates often bear prominent spines, like teeth, making the edges of the starfish very spiny.
(From Cronodon.com)