''Receptaculites'' is the name-bearing genus for an extinct group of conspicuous benthic marine genera, the receptaculitids (formally Receptaculitaceae or Receptaculitidae), that lived from the Early

Ordovician The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. T ...

through the

Permian The Permian ( ) is a geologic period and System (stratigraphy), stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last ...

period, peaking in the Middle Ordovician. The group's phylogenetic origin has long been obscure, with some arguing that they were calcareous algae, probably of the order

Dasycladales Dasycladales is an order of large unicellular green algae in the class Ulvophyceae. It contains two families, the Dasycladaceae and the Polyphysaceae. These single celled algae are from 2 mm to 200 mm long. They live on substrates ...

.Byrnes, J.G. 1968. Notes on the nature and environmental significance of the Receptaculitaceae. Lethaia, vol. 1, p. 368-381. Receptaculitids lived in warm, shallow seas, but consensus disagreeing. They have been described from all continents except Antarctica. In some areas they were important reef-formers, and they also occur as isolated specimens. KimmswickOzoraMidOrdReceptaculitid

''Receptaculites'' and its relatives have a double-spiral, radiating pattern of

rhombus In plane Euclidean geometry, a rhombus (plural rhombi or rhombuses) is a quadrilateral whose four sides all have the same length. Another name is equilateral quadrilateral, since equilateral means that all of its sides are equal in length. The ...

-shaped plates supported by spindle-like objects called meroms. Fossils can usually be identified by the intersecting patterns of clockwise and counterclockwise rows of plates or stalk spaces, superficially similar to the arrangement of disk

floret This glossary of botanical terms is a list of definitions of terms and concepts relevant to botany and plants in general. Terms of plant morphology are included here as well as at the more specific Glossary of plant morphology and Glossary o ...

s on a sunflower—hence the common name "sunflower coral" (''sic''). Receptaculitids have sometimes been compared to the morphologically similar, but probably distantly related,

cyclocrinitids Cyclocrinitids are an early (mid-Ordovician–early-Silurian) Dasycladalean algae, resembling but probably not closely related to the Receptaculitids. References Dasycladales {{silurian-plant-stub ...

References

{{Taxonbar, from=Q7302354 Paleozoic plants Ulvophyceae genera Fossil algae Early Ordovician first appearances Permian genus extinctions Paleozoic life of Ontario Paleozoic life of Alberta Paleozoic life of British Columbia Paleozoic life of Manitoba Paleozoic life of Newfoundland and Labrador Paleozoic life of the Northwest Territories Paleozoic life of Nunavut Paleozoic life of Quebec