''Margaretia'' is a frondose organism known from the middle Cambrian

Burgess shale The Burgess Shale is a fossil-bearing deposit exposed in the Canadian Rockies of British Columbia, Canada. It is famous for the exceptional preservation of the soft parts of its fossils. At old (middle Cambrian), it is one of the earliest fo ...

and the Kinzers Formation of

Pennsylvania Pennsylvania (; ( Pennsylvania Dutch: )), officially the Commonwealth of Pennsylvania, is a state spanning the Mid-Atlantic, Northeastern, Appalachian, and Great Lakes regions of the United States. It borders Delaware to its southeast, ...

. Its fronds reached about 10 cm in length and are peppered with a range of length-parallel oval holes. It was originally interpreted as an alcyonarian

coral Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and ...

. It was later reclassified as a green alga closely resembling modern ''

Caulerpa ''Caulerpa'' is a genus of seaweeds in the family Caulerpaceae (among the green algae). They are unusual because they consist of only one cell with many nuclei, making them among the biggest single cells in the world. A species in the Mediterran ...

'' by D.F. Satterthwait in her Ph.D. thesis in 1976,Donna Fields Satterthwait, Paleobiology and Paleoecology of Middle Cambrian Algae from Western North America, Ph.D. Thesis University of California at Los Angeles, 1976. a finding supported by Conway Morris and Robison in 1988.S.Conway Morris and R.A. Robison, "More soft-bodied Animals and Algae from the Middle Cambrian of Utah and British Columbia", University of Kansas Paleontological Contributions, Paper 122, pages 8-11, 1988

/ref> More recently, it has been treated as an organic tube, that is used as nest of hemichordate ''

Oesia ''Oesia disjuncta'' is a monospecific genus known from the Middle Cambrian Burgess Shale. 1147 specimens of ''Oesia'' are known from the Greater Phyllopod bed, where they comprise 2.18% of the community. Despite some similarities to the chaetogn ...

''.

References

External links

* Burgess Shale fossils Wheeler Shale Incertae sedis {{cambrian-stub