SEA-URCHIN SHELL

Above you see something found occasionally along the beach here. Can you imagine what it is -- animal, vegetable or mineral? The first time I found such a thing I was completely stumped until one day one turned up bearing long, slender, black spines weakly attached to each bump on the shell's surface. Instantly I realized it was a sea-urchin -- or rather a dead sea-urchin's bleached, de-spined shell.

Living sea-urchins look like the business ends of medieval battle-maces. A living one is shown here.

In fact, the one shown above, Lytechinus variegatus, may well be the species whose shell I've photographed. I'm basing that on a tentative ID made with a reef- animal field guide found in the hotel's reception room.

Wikipedia does a pretty good job providing an overview of sea-urchin life history at http://en.wikipedia.org/wiki/Sea_urchin.

Below is a shell with many of the spines still attached.