Coniconchia

Coniconchia [‚kän·ə′käŋ·kē·ə]

(paleontology)

A class name proposed for certain extinct organisms thought to have been mollusks; distinguished by a calcareous univalve shell that is open at one end and by lack of a siphon.

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Coniconchia 

a group of extinct organisms. The taxonomic position of the Coniconchia is uncertain; they have conditionally been assigned to the phylum Mollusca. Their remains are known from deposits of the Cambrian to the Permian epochs. As a rule, they had conical shells, divided in the initial part into chambers by crosswise barriers. The shells measure from a few mm to 15 cm. Some scientists consider the Coniconchia a class with the superorders Tentaculitoidea and Hyolithoidea; others consider the last two to be independent classes. The genera and species of Coniconchia are important index forms for subdividing and comparing deposits of the Cambrian to Devonian epochs.

REFERENCE

Osnovy paleontologii: Molliuski-golovonogie, vol. 2. Moscow, 1958.