Limpet
2 of the 7 encyclopedias on this shelf carry an entry for Limpet. Both are reproduced below, so you can see where they agree and where they differ.
Collier's New Encyclopedia (1921)
a popular name for any of the prosobranchiate gasteropods of the family Patellidæ and (more properly) of the genus Patella. The shell is usually oval and tent-shaped; interior smooth, but not nacreous. Limpets are world- Hon. They are inhabit rocks bewide in their distribution. They are ning to the same vegetable feeders, and inhabit rocks behey are much used tween tidemarks, returning to the same and in times of place after feeding. They are much used et quantities fall a by fishermen for bait, and in times of shore birds. The scarcity for food. Vast quantities fall a atopus ostralegus) prey to the sea and shore birds. The rous in detaching oyster catcher (Hæmatopus ostralegus) rocks, and scoopis exceedingly dexterous in detaching their shells. these mollusks from the rocks, and scooping the animals from their shells. of England and a al of Lincolnshire;
Aiton's Encyclopedia (1910)
a small, conical shellfish. The shell is much like that of one-half of a clamshell surrounded by a leathery fringe or border. The limpet fills the shell and clings by its exposed side to a rock. By raising the middle of its body slightly it creates "suction" and is held so firmly to the rock by atmospheric pressure that it is not easy to pick it off. At low tide British fishermen gather limpets for bait, and millions are collected on the Irish coast for food. Limpets go about when the tide is in, feeding on seaweeds which they rasp away with a rough file-like tongue. It is said a limpet "homes," or returns to the same spot on a rock, till it oftentimes wears a depression.