Priapulida: Meaning (information, definition, explanation, facts)

Priapulida (priapulid worms, or penis worms) are a phylum of marine worms with an extensible spiny proboscis. Priapulid fossils are known at least as far back as the Middle Cambrian. There nearest relatives are probably Kinorhyncha and Loricifera with which they constitute the taxon Scalidophora. Since 2004 fossil worms have become known that seem to be stem group representatives of that taxon. They are placed in two species in the genus Markuelia.