Hyolitha

Haplophrentis

• Worldwide

The Hyolithiden or Calyptomatida are a group of animals that existed in the Lower Cambrian to the Middle Permian and became extinct at the end. Widely used in the Cambrian and Ordovician they obtained, but often also in many places in the Silurian and Devonian, rare in the Carboniferous and Permian.

Their systematic position is not precisely known. They are assigned to the tribe of mollusks and are also called floating worm or Urmollusken. Hyolithiden form bilaterally symmetric, up to 15 cm long tapered calcareous triangular, elliptical, circular, or pentagonal cross section. One side is usually flattened, bulging or provided with a blunt keel others. To close the mouth is used in most representatives of a concentric striped lid.

About your ecology can not say anything more accurate, but because of the soft body preservation of paired fin-like attachments in some species a free-floating lifestyle is adopted. A sessile, anchored to the seabed, lifestyle is also conceivable, in which they have stuck with the tip first in soil sediment. Probably it was benthos shallow seas, living on organic suspended solids. Natural enemies were Priapswürmer the type Ottoia prolifica, which are found in the Cambrian Burgess Shale of.