Emeraldella  Emeraldella is a genus of arthropod known from the Middle Cambrian of North America. The type species "E. brocki" was described in 1912 from the Burgess Shale. A re-study on the species was done in 2012. A second species "E. brutoni" is known from the Wheeler Shale, which was described in 2011. An additional specimen of "E. brutoni" was described in 2019, which revealed more of the anatomy. "E. brocki" is up to 60 mm in length, it possesses 12 tergites in the trunk section, with an extended telson. The attenula are long and can reach the length of the body, and are composed of more than 80 segments. Ocular structures appear to be absent in this species. "E. brutoni" is up to 50 mm in length, it possesses 10 trunk tergites, and possesses clear ocellii, unlike "E. brocki", the antennae are not preserved well enought to tell true length.