''Calclamnoidea'' is an extinct genus of

sea cucumber Sea cucumbers are echinoderms from the class (biology), class Holothuroidea ( ). They are benthic marine animals found on the sea floor worldwide, and the number of known holothuroid species worldwide is about 1,786, with the greatest number be ...

which existed in

Poland Poland, officially the Republic of Poland, is a country in Central Europe. It extends from the Baltic Sea in the north to the Sudetes and Carpathian Mountains in the south, bordered by Lithuania and Russia to the northeast, Belarus and Ukrai ...

during the

Triassic The Triassic ( ; sometimes symbolized 🝈) is a geologic period and system which spans 50.5 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.4 Mya. The Triassic is t ...

period.Triassic Holothurian Sclerites from Tatra Mountains
Krystyna Zawidzka.

References

Fossils of Poland Calclamnidae Prehistoric sea cucumber genera Triassic echinoderms Middle Triassic first appearances Late Jurassic extinctions Fossil taxa described in 1955 {{Paleo-holothuroidea-stub