''Archotuba'' is a genus of elongated conical tubes that were seemingly deposited by colonial organisms. Known from the Chengjiang, its biological affinity is uncertain; it somewhat resembles the tubes of the ' priapulid' ''

Selkirkia ''Selkirkia'' is a genus of predatory, tubicolous priapulid worms known from the Middle Cambrian Burgess Shale, Ogygopsis Shale and Puncoviscana Formation. 142 specimens of ''Selkirkia'' are known from the Greater Phyllopod bed, where they compr ...

'', but a

cnidarian Cnidaria () is a phylum under kingdom Animalia containing over 11,000 species of aquatic animals found both in freshwater and marine environments, predominantly the latter. Their distinguishing feature is cnidocytes, specialized cells that th ...

affinity is also possible. In the absence of soft parts, there really isn't enough data to confirm a biological affiliation.

''Archotuba elongata''

The extinct species ''Archotuba elongata'' is a debated priapulid from the Early Cambrian, discovered by Luo and Hu in 1999. Recorded only in the

Chengjiang Biota The Maotianshan Shales are a series of Early Cambrian deposits in the Chiungchussu Formation, famous for their '' Konservat Lagerstätten'', deposits known for the exceptional preservation of fossilized organisms or traces. The Maotianshan Shales ...

Yunnan Province Yunnan , () is a landlocked province in the southwest of the People's Republic of China. The province spans approximately and has a population of 48.3 million (as of 2018). The capital of the province is Kunming. The province borders the C ...

, this species was initially found to be part of the phylum

Priapulida Priapulida (priapulid worms, from Gr. πριάπος, ''priāpos'' 'Priapus' + Lat. ''-ul-'', diminutive), sometimes referred to as penis worms, is a phylum of unsegmented marine worms. The name of the phylum relates to the Greek god of fertility ...

, but some have raised the question that ''A. elongata'' may be related to the cnidarians. In fact, due to the lack of soft body preservation, not only does confusion remain as to the placement of ''A. elongata'', the another described species, ''Archotuba conoidalis'', has been found to be a synonym of ''A. elongata''. The available specimens consist of hundreds of compressed tubes, white with some rust-colored blotches, each in shape a long cone at most 5 cm in length and 6 mm in width. The posterior is pointed, but save for a few rare annulations, the fossil is unadorned. The creature's intestine is visible along its midline, and its dark color may indicate a carnivorous nature. The habits of ''A. elongata'' are disputable: a popular explanation is that because this species is often found fixed to other creatures, and even clustered together with its own kind in similar orientations, it perhaps did not move, highly unlike the current understanding of priapulids. However, if indeed they were sedentary like the cnidarians, no tentacles have been preserved to support such a conjecture.

References

{{authority control Prehistoric animal enigmatic taxa Fossil taxa described in 1999 Enigmatic prehistoric animal genera