barnacle

n. marine crustacean which permanently fixes itself to rocks

A barnacle is a type of arthropod belonging to infraclass Cirripedia in the subphylum Crustacea and is hence distantly related to crabs and lobsters. Some authorities regard Cirripedia as a full class or subclass, and the orders listed at right are sometimes treated as superorders. Around 1,220 barnacle species are currently known. The name "Cirripedia" is Latin, meaning "curl-footed".
See more at Wikipedia.org...

Noun
1. marine crustaceans with feathery food-catching appendages; free-swimming as larvae; as adults form a hard shell and live attached to submerged surfaces
(synonym) cerriped, cerripede
(hypernym) crustacean
(hyponym) acorn barnacle, rock barnacle, Balanus balanoides
(member-holonym) Cirripedia, subclass Cirripedia
2. European goose smaller than the brant; breeds in the far north
(synonym) barnacle goose, Branta leucopsis
(hypernym) goose
(member-holonym) Branta, genus Branta

n. barnacle, marine crustacean which permanently fixes itself to rocks

(sing.)
Spectacles; -- so called from their resemblance to the barnacles used by farriers.
  

(n.)
Any cirriped crustacean adhering to rocks, floating timber, ships, etc., esp. (a) the sessile species (genus Balanus and allies), and (b) the stalked or goose barnacles (genus Lepas and allies). See Cirripedia, and Goose barnacle.
  

(n.)
An instrument for pinching a horse's nose, and thus restraining him.
  

(n.)
A bernicle goose.