Chelycypraea testudinaria, common name the tortoise cowry, is a species of sea snail, a cowry, a marine gastropod mollusk in the family Cypraeidae, the cowries.
The shells of these quite uncommon cowries reach on average 90–110 millimetres (3.5–4.3 in) of length, with a minimum size of 75 millimetres (3.0 in) and a maximum size of 142 millimetres (5.6 in). They are variable in pattern and color. The shape is oval or sub-cylindrical, the dorsum surface is smooth and shiny, the basic color is whitish or yellowish and it is covered by very irregular dark brown patches and spots. The margins are white or pale brown, with some large dark dots. The base may be whitish, pale brown or pink, the aperture is long and narrow and the teeth are white, short and fine. In the living animal the mantle is bluish-greyish and almost transparent, while the sensorial papillae are lighter and rather long. The mantle and foot are well developed. The lateral flaps of the mantle can completely hide the dorsum surface.