Plural of conch; large spiral shells of sea snails, often used as musical instruments or decorative objects.
From Greek konche (shell). The word has been used in English since at least the 1500s for these distinctive large shells.
Conchs were literally ancient horns—people blew into them to signal, and the sound carries incredibly far underwater, which is why sea creatures might flee when they hear one!
Complete word intelligence in one call. Free tier — 50 lookups/day.