whorl
shell structure
Also known as: coil
Quick Summary
A whorl is a term used to describe a spiral or coil. In the context of shells, particularly those of snails, a whorl refers to one of the turns of the spiral that makes up the shell.1
The typical snail shell is coiled around a central axis called the columella. As the snail grows, it adds larger coils, or whorls, to its shell. The last and outer whorl of a univalve shell is specifically known as the body whorl. These shells are made of calcium carbonate and are secreted by the mantle, the fleshy part of the animal.23
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