Priapulida (
priapulid worms or
penis worms, from Gr. πριάπος,
priāpos '
Priapus' + Lat.
-ul-, diminutive) is a
phylum of marine
worms. The name of the phylum relates to the Greek god of fertility, because their general shape and their extensible spiny introvert (eversible
proboscis) may recall the shape of a penis. They live in the mud (which they eat) and in comparatively shallow waters up to deep. Some species show a remarkable tolerance for
hydrogen sulfide and
anoxia.