Bicellum

Bicellum is a genus of fossil holozoans containing the single species Bicellum brasieri.^[1] It is one billion years old and could be the oldest example of complex multicellularity in the evolutionary lineage leading to the animals,^[2][3] and has been described as bridging "the gap between the very first living creatures — single-celled organisms — and more complex multicellular life."^[4] It was discovered in 2021, and is posthumously named after the late Martin Brasier, a paleontologist who was a co-author of the paper that first described it.^[5]

Bicellum Temporal range: 1000 Ma Pha. Proterozoic Archean Had. ↓
Multiple specimens of B. brasieri, such as the holotype (A)
Scientific classification
Domain:	Eukaryota
Clade:	Amorphea
Clade:	Obazoa
Clade:	Opisthokonta
Clade:	Holozoa
Genus:	†Bicellum
Species:	†B. brasieri
Binomial name
†Bicellum brasieri Strother et al. 2021[1]

Fossil site

Bicellum was found in sediments from the Diabaig Formation in Loch Torridon, Scotland. The Diabaig Formation, considered to represent an ancient lake deposit,^[6] was already known to preserve the first non-marine eukaryotes.^[7]