Tripneustes depressus is a species of sea urchin in the family Toxopneustidae, commonly known as the white sea urchin or Pacific white urchin. It is a marine echinoderm native to the eastern Pacific Ocean, ranging from the Gulf of California along the Pacific coasts of Mexico and Central America to Peru and the Galápagos Islands. It inhabits shallow coastal waters, seagrass beds, and rocky substrates. The genus name Tripneustes derives from Greek, combining tri- meaning “three” and pneustes meaning “breather”, referring to structural features of its test and ambulacral system, while the species epithet depressus is Latin for “flattened,” describing its relatively low, flattened profile to related species.

Historically, this species has been harvested by coastal communities in Mexico, Peru, and Ecuador for its edible gonads, which are consumed fresh. In modern times, it is marketed as uni, both locally and for export, and is increasingly subject to fishery management and aquaculture research due to high international demand. It is particularly associated with Pacific Mexican and Peruvian coastal food traditions, where it may be eaten fresh with lime or incorporated into ceviche-style preparations.

Nutritionally, Tripneustes depressus contains eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), omega-3 fatty acids known for anti-inflammatory and cardioprotective effects; echinochrome A, a polyhydroxylated naphthoquinone pigment with antioxidant properties; ovothiol, a sulfur-containing antioxidant compound; and carotenoids such as β-carotene and astaxanthin, which contribute to coloration and oxidative stability. These compounds contribute both to its nutritional value and to potential protective effects against oxidative stress, although like other marine invertebrates it can bioaccumulate environmental contaminants depending on habitat conditions.