Brooksella alternata

Brooksella alternata is a species of lobate Cambrian fossil sponge found in the Conasauga Formation of Alabama and Georgia.[1] These fossils are often referred to as "star-cobbles" for their distinct lobate appearance, generally with 6 or more lobes.

Brooksella alternata
Temporal range: Middle Cambrian
Brooksella alternata (fossil sponge) (Cambrian, Alabama, USA).jpg
Scientific classification edit
Kingdom: Animalia
Phylum: Porifera
Class: Hexactinellida
Order: Reticulosa
Family: Protospongiidae
Genus: Brooksella
B. alternata
Binomial name
Brooksella alternata
Walcott, 1896

Brooksella alternata was first described in 1896 by Charles Walcott, who believed them to be medusoid body fossils of cnidarians.[2][3]

Later researchers have offered other explanations, from diagenetic gas bubbles to burrow traces. The most accepted identity is that they are hexactinellid sponges, based on observed spicules, ostia, and internal structure.[1]


  1. ^ a b Ciampaglio, Charles N.; Babcock, Loren E.; Wellman, Carrie L.; York, Angela R.; Brunswick, Holly K. (August 2006). "Phylogenetic affinities and taphonomy of Brooksella from the Cambrian of Georgia and Alabama, USA". Palaeoworld. 15 (3–4): 256–265. doi:10.1016/j.palwor.2006.10.002.
  2. ^ Walcott, Charles (1896). "Fossil Jelly Fishes from the Middle Cambrian Terrane". Proceedings of the United States National Museum. 18 (1086): 611–614. doi:10.5479/si.00963801.18-1086.611.
  3. ^ Walcott, Charles (1898). "Fossil Medusae" (PDF). Monographs of the United States Geological Survey. XXX.