The Lightning Whelk is one of the most popular shells among collectors in Florida. Taking live shells is not permitted on Sanibel Island, so I returned this one to the water after taking its photo. The black part inside the shell is the “foot” of the live animal, used for locomotion, with the soft body parts hidden behind it. The foot has yellow flesh covered with black skin. The oval, shell-like piece in the middle is called the operculum and is attached to the animal’s foot. When the whelk withdraws into the shell, the operculum acts like a trap door and seals the animal safely inside. This is the only Florida shell which is “left-handed”. That means if you held it with the tip down, your left hand would naturally slide inside the empty shell. While they can grow to 20 inches, this one was only about 8 inches long.