ClipArt ETC
"A helmet; a casque. The helmet was originally made of skin or leather, whence is supposed to have arisen its appellation, meaning properly a helmet of dog-skin, but applied to caps or helmets made of the hide of other animals, and even to those which were entirely of bronze or iron. The five following helmets are selected from antique gems, and are engraved of the size of the originals." — Smith, 1873.

Galea

"A helmet; a casque. The helmet was originally made of skin or leather, whence is supposed to have arisen…

"Found in the Mediterranean, generally on reefs." — Goodrich, 1859

Dolium galea

"Found in the Mediterranean, generally on reefs." — Goodrich, 1859