Sipunculus nudus is a marine invertebrate belonging to the family Sipunculidae, commonly known as a peanut worm due to its rounded, unsegmented body shape when contracted. It is widely distributed in sandy and muddy coastal environments of temperate and tropical seas, including parts of East Asia, Europe, and the Indo-Pacific. The genus name Sipunculus derives from Latin sipunculus, meaning “little tube” or “small siphon,” referring to the animal’s retractable introvert used for feeding and respiration, while the species epithet nudus means “naked,” describing its smooth, unsegmented body lacking obvious external appendages.

Sipunculus nudus lives buried in sediment or within crevices, extending its introvert to gather organic particles, detritus, and microorganisms from the surrounding substrate. It plays an ecological role as a deposit feeder, contributing to sediment turnover and nutrient cycling in benthic ecosystems. The body consists of a thick trunk and a retractable anterior section equipped with tentacles surrounding the mouth, which assist in feeding.

As a food source, Sipunculus nudus has been traditionally consumed in certain coastal regions of East and Southeast Asia. It is particularly known in parts of China, where it is used in soups, broths and porridges, often valued for its chewy texture and perceived nourishing qualities. The organism is typically cleaned, sometimes dried, and then rehydrated or cooked fresh. Its mild flavor allows it to absorb seasonings, making it suitable for slow-cooked dishes.

Nutritionally, Sipunculus nudus is high in protein and low in fat, containing essential amino acids and minerals such as calcium, iron, and zinc. It also contains collagen-like proteins and marine-derived peptides that have been studied for potential antioxidant and bioactive properties in experimental settings. As with other marine invertebrates, proper cleaning and cooking are important to ensure safety and palatability.