The surface of the shell is smooth, shiny and completely snow white, with a dark reddish-purple interior, visible through the wide and long aperture, which bears teeth on one side only.

In the living cowries the mantle is black, with a pattern of small white spots in adults, while juveniles resemble some toxic nudibranchs of the genus Phyllidia owing to their orange yellow sensorial papillae.

This species is distributed in the Red Sea and in the Indian Ocean along East Africa (Aldabra, Madagascar, Mozambique, Mauritius, Tanzania, Kenya, Chagos) and in Western and Central Pacific Ocean (New Zealand, Australia, North Sulawesi, Malaysia, Borneo, New Caledonia, Philippines, French Polynesia and southern Japan).

Ovula ovum lives in tropical reef in shallow waters at 2 to 20 metres (7 to 66 ft) of depth, usually on algae or soft corals, mainly feeding on Alcyonarian colonies (Leather Coral, genus Sarcophyton and Sinularia sp., Alcyoniidae).

Ovula ovum eats the sponge Sarcophyton, despite it containing the toxic terpene macrolide sarcophytoxide.