bonnethead

[ bon-it-hed ]
/ ˈbɒn ɪtˌhɛd /

noun

a hammerhead shark, Sphyrna tiburo, found in shallow waters from Brazil to Massachusetts, having a spade-shaped head.
Also called bonnet shark, shovelhead.

Origin of bonnethead

An Americanism dating back to 1875–80; bonnet + head