Cloacaspis is an extinct genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of Olenid Ptychopariid

Ptychopariida

Ptychopariida is a large, heterogeneous order of trilobite containing some of the most primitive species known. Many date to the Early Cambrian Period, but the order was extant through the Late Ordovician...

 trilobite

Trilobite

Trilobites are a well-known fossil group of extinct marine arthropods that form the class Trilobita. The first appearance of trilobites in the fossil record defines the base of the Atdabanian stage of the Early Cambrian period , and they flourished throughout the lower Paleozoic era before...

. It lived during the early part of the Arenig stage

Arenig

In geology, the Arenigian refers both to a time interval during the Lower Ordovician period and also to the suite of rocks which were deposited during this interval.-History:...

 of the Ordovician Period, a faunal stage

Faunal stage

In chronostratigraphy, a stage is a succession of rock strata laid down in a single age on the geologic timescale, which usually represents millions of years of deposition. A given stage of rock and the corresponding age of time will by convention have the same name, and the same boundaries.Rock...

 which lasted from approximately 478 to 471 million years ago. Richard Fortey

Richard Fortey

Richard A. Fortey FRS is a British palaeontologist and writer.-Career:Richard Fortey studied geology at the University of Cambridge and had a long career as a palaeontologist at the Natural History Museum in London. Prof. Fortey’s research interests include, above all, trilobites...

has proposed that these particular trilobites lived in anoxic regions of the ocean floor, and cultivated symbiotic, sulfur-metabolizing bacteria.

Etymology

The generic name is a compound word from Latin, "cloaca," meaning sewer, and from Greek, "aspis," meaning "shield." Thus, Cloacaspis translate as "sewer shield." In his book, Trilobite! Eyewitness to Evolution, Fortey, who first discovered the genus in Ordovician strata in Spitsbergen, explained that the rocks they were found in had a rank, sulfurous odor, reminding him of raw sewage.