Lyncina vitellus, common name : the calf cowry or the Pacific deer cowry, is a species of sea snail, a cowry, a marine gastropod mollusk in the family Cypraeidae, the cowries.
The shells of these very common cowries reach on average 35–45 millimetres (1.4–1.8 in) of length, with a minimum size of 20 millimetres (0.79 in) and a maximum size of 100 millimetres (3.9 in). The shape is usually pear-shaped, the dorsum surface is smooth and shiny and may be pale or dark brown, with several small white spots. The margins and the extremities are clearer, while the base is generally white, with a wide sinuous aperture and long labial teeth. The margins show also numerous thin vertical whitish lines. The juvenile forms have two-three clearer trasversal bands on the shell dorsum. These shells are quite similar and may be confused with the shells of Lyncina camelopardalis. In the living cowries the mantle is grey-brown and almost transparent, with long whitish tree-shaped papillae. Mantle and foot are very well developed, usually with external antennae.