What are barnacles?

   Anyone who goes to the seashore is likely to see many of the little ani­mals called barnacles. Barnacles are found on rocks along the seashore. They are found, too, on floating logs, on piers, on the bottoms of ships, and even on other ani­mals. Seashells picked up on the shore may have tiny barnacle shells fastened to them.
Barnacles are cousins of the lobsters and the crabs, but they do not look much like these cousins of theirs. The barnacles that grow on rocks look like tiny volcanoes. Those that grow on ships have stalks. They are often called goose barnacles.
   Barnacles may be crowded closely together. More than 2,000 have been found growing on a rock in a space no bigger than one square ft. So many may grow on the bottom of a ship that they have to be cleaned off.
Baby barnacles swim about freely. But soon they fasten themselves to something solid and grow a shell. Barnacles stay for the rest of their lives in the place where they settle.
   A barnacle never leaves its shell. It never even sticks its head out. But it does put its feathery feet out through the opening in its shell. These feet kick tiny plants and animals into its mouth. When a barnacle is not covered with water, it pulls in its feet and closes its shell.