Marrella is a marrellid marrellid marrellomorph arthropod from the Cambrian Series 3 of Canada. It was named in 1912 by Charles Doolittle Walcott. It was the most common arthropod in Cambrian Canada, and it was thought to be either a trilobite, chelicerate, or crustacean, before finally being discovered to be an arthropod of its own class.
Physiology[]
Marrella had a body plan very similar to modern arthropods. It has a segmented body (comprised of 26 body segments), 4 pairs of walking legs, 2 feathery gills near its head, 2 pairs of antenna (1 pair is long, while the other is short), and a head shield with 2 pairs of backwards-facing spines protruding from it. Its body would have been covered in a hard, chitinous exoskeleton.
Diet[]
Marrella was a scavenger, feeding on the dead bodies of other arthropods like trilobites. However, it would also sometimes settle for detritus suspended on the seafloor.
Ecology[]
Marrella was once thought to be a crustacean (often called a lace crab), right before being hypothesized to be a trilobite, due to its flat shape and spines. However, none of these hypotheses are correct, as it was later classified as an arthropod of its own class, due to having too many antenna, too few legs, and too few segments per leg to be a trilobite. Marrella was a bottom-feeder living on the seafloor, feeding on any piece of organic debris found there. As well as this, it would sift through the seafloor to find organic particles to eat.