fiddle-head (n.)

also fiddlehead, "one with a head as hollow as a fiddle," 1854 (fiddleheaded), from fiddle (n.) + head (n.). As a name for young fern fronds, from 1877, from resemblance to a violin's scroll. Earliest use is nautical, "carved ornamental work at the bow of a ship in the form of a scroll or volute" (1799).

There are three kinds of heads,--1st The Figure-head is one on which is placed the figure of a man, woman, or the like, &c.; 2d, The Billet-head, or Scroll-head is one finished with two scrolls or volutes ...; and 3d, the Fiddle-head, which is finished with only one scroll or volute, having the spirals turning inwards to the vessel. [Peter Hedderwick, "Treatise on Marine Architecture," Edinburgh, 1830]