lamprey (n.)

c. 1300 (perhaps c. 1200 as a surname), from Old French lamproie "lamprey" (12c.), from Medieval Latin lampreda, from Late Latin lampetra "lamprey," a word of uncertain origin, usually explained as literally "lick-rock," from Latin lambere "to lick" (see lap (v.1)) + petra "rock" (see petrous), but this might be folk etymology. The animals attach themselves with sucker-like mouths.