Hip'po-cāmp, n.

noun

n. [Lat. hippocampus, Gr. ἱπποκαμπος, ἱπποκάμπη, from ἵππος, horse, and κάμπτειν, to bend.] The sea-horse. Browne.

A seahorse is shown curled into a spiral.
Hippocampus.