[5] Along with the other Cambrian worms such as Ottoia, Selkirkia, Louisella, Fieldia, Scolecofurca, and Lecythioscopa, the organism may fall into a clade termed "Archaeopriapulida," a stem group to the Priapulids proper.

[7] A phylogenetic analysis does not provide a great deal of resolution to the relationships between these basal worms.

Tolkien's Middle-earth legendarium, in reference to the worm's prominent rows of hooks on its proboscis.

The trunk is annulated with 0.2 to 0.25 millimeter spacing, and carried rows of setae possibly performing sensory functions.

The apparent absence of retractor muscles correlates with Ancalagon's inability to significantly invert its proboscis.