Genevievella Trilobites

Genevievella is a genus of trilobites found in Upper Cambrian strata of the United States and Canada.  One of their most distinctive features is a back-wards projecting spine on the 8th thoracic segment, probably used to deter predators when they roll up.  Surrounding these two specimens are small patches of branching, frondose bryozoans, intermixed with orange colonial tunicates similar to modern day Botrylloides.  The weird creatures in the tubes are meant to be snails based on the modern day snail Serpulorbis squamigerus, whose shells grow "straightened" as opposed to coiled.  Also look for a couple of tiny nudibranchs based on Thuridillia neona.