Enjoy a few more exciting photos like this at :SE Littoral Society Invertebrates page
. . . and, by all means, double-click to make the photo larger.
"The horse conch (Pleuroploca gigantea), also known as the giant band shell, has been Florida's official state shell since 1969. This shell is native to the marine waters around Florida and can grow to a length of twenty-four inches. Young horse conchs have orange-colored shells; adults have orange apertures.
At least 535 million years ago, mollusks acquired the ability to secrete a carbonate of lime solution that formed a hard, protective shell around them. The word "conch" comes from a Greek word meaning "shell.", "
- Florida Division of Historical Resources