Teinostoma carinicallus is one the most distinctive among the local species of vitrinellas (family Tornidae). Its shell, which rarely reaches 3 mm (0.12 inch) in diameter, is delicate, smooth, with a low spire. The last whorl is flat, but the shell periphery is rounded. A concave callus (the plug-like structure on the shell base) completely closes the shell umbilicus. The most distinctive feature in the shell of this species is the presence of a narrow keel bordering the callus. The shell color is translucent-white. The shell in the illustration was collected by Phyllis Sharp in 2004 at the Lighthouse Beach on Sanibel. Photos by James F. Kelly.