Mollisonia

[1][2] The genus is characterized by a capsule-like dorsal exoskeleton (tergites), which was divided into a subequal size of cephalon and pygidium with 7 thoracic segments in between.

As a Cambrian arthropod, the genus is significant by bearing several traits of now-surviving chelicerates, such as pincer-like mouthparts (chelicerae) and fused ring-like cephalic nerves (synganglion) within their head, as well as a series of multilayered book gills underneath their trunk appendages.

[1][2] Mollisonia may had been a benthic predator, using its anterior chelicerae and posterior gnathobasic limbs to devour prey items while using the 6 legs to walk around the sea floor.

[1] Three species (P. symmetrica, P. gracilis, P. plenovenatrix) are known from the Burgess Shale, with 21 specimens are known from the Greater Phyllopod bed, where they comprise less than 0.1% of the community as of 2006.

[3] The genus is also known from Langston Formation, and Wheeler Shale of North America, as well as Chengjiang Biota of China (P.

Mollisonia symmetrica in various views showing digestive (cyan) and nervous systems (purple)