98 LIFE AND HER CHILDREN. 
snapping claws to clear away any refuse which may 
gather on the shell. Lastly, the sea-urchin, which, 
like the star-fish, often protects its young ones in their 
soft infancy, will sometimes gather the spines together 
at the top of its house, and so form a tent for the 
tender young urchins till they are fit to go alone. 
The snapping claws, which we found before in the 
star-fish, exist in numbers on the shell of the Echinus, 
and are very puzzling ; they are so very active and 
yet seem to do so little work. They have often, 
however, been seen passing away the little pellets of 
refuse food which come out of a hole in the top of 
the shell. These pellets are handed down from claw 
to claw till they can be dropped into the water and 
so got rid of. In the same way small worms and 
seeds of plants and other living things are cleared off 
the bristling shell by these busy little snapping beaks. 
The spines by their constant movement help, as we 
have seen, in this cleaning process, and have probably 
many uses not known to us. 
Who will say when he examines the structure and 
studies the habits of the Echinus, that this child of 
life is not a quaint, clever, wonderful, and skilful 
piece of mechanism, as it lives and breeds by 
thousands in the depths of the sea ? Any handful of 
seaweed out of a pool at low tide will contain some, 
so small as hardly to be noticed ; while from the 
rocky depths of the Mediterranean the fishermen 
bring up large ones in order to sell their bunches 
of eggs for food. Yet, as they stand in the Italian 
markets feebly moving their spines round and round 
in search of some of the old familiar objects in their 
sea -home, how few people stop to examine the 
