Five-fingers has a great number of cousins, some of them common enough along our shores.  One of the strangest is the Brittle Star.  On first seeing one of these animals I tried to capture it by holding its long, wriggling arms.  At once the arms broke off.  Then I tried to scoop the creature out of its watery home.  But it began to break its “rays” off as if they were of no value whatever.  To my surprise, the broken “rays” broke again while wriggling on the ground.  This is a strange habit, is it not?  Perhaps the Brittle Star has found this dodge useful in escaping from enemies.  Anyhow, the loss of an arm or two matters little, for others grow in their place.

Another cousin of the Starfish is the Sea-urchin, a round prickly creature rather like the burr of the sweet-chestnut tree.  This mass of prickles is not a vegetable; he is very much alive.  Nature has given many plants and animals these prickles, like fixed bayonets, for a defence against their enemies.  You will at once think of the gorse and the hedgehog, or urchin, as some people call it.  Our little Sea-urchin has prickles, like the hedgehog, but he is really unlike any other living creature, except, perhaps, the Starfish.

If you were to roll up a Starfish into a ball, and then stick about three thousand spines on the ball thus made, you would have a creature looking rather like a Sea-urchin.

Beneath the mass of spines there is a hard test or shell, made of plates joined closely together; this is the skeleton of the Sea-urchin.  Sometimes you find this strange shell on the seashore, rather dirty, and not always sweet-smelling.  You might also find Sea-urchins half-dead, washed into the rock-pools.  The shells are wonderful objects, so you should clean them in fresh water; they are well worth the trouble of taking home.

All over the shell you will see little rounded knobs.  These show where the spines were fixed on; each spine fits into a hole in the shell, but so loosely that it is able to move about.  The Sea-urchin can walk by moving its spines, tilting its body along from one place to another on the bed of the sea.  It can do much more than that.  Like its cousin the Starfish, it has numerous tube-feet, so you would not be surprised to see this prickly ball walk up the face of a rock.

The tube-feet, or sucker-feet, are fixed to the shell in much the same way as the spines.  They can be bent this way or that.  If the Urchin is on a rock he clings tightly with these sucker-feet; then, if he wishes to move away, you will see the long thin tubes stretch out and bend about.  They fix themselves to the rock, and the animal is drawn along.

[Illustration:  Test or shell of A sea-urchin.]