Scathascolex
Scathascolex is a genus of palaeoscolecid worm known from the middle Cambrian Burgess Shale. It is the only taxon in that famous locality to exhibit the phosphatic plates that characterize palaeoscolecids, and has certain unusual characteristics – it does not have the multiple sizes of tessellating plates more typical of palaeoscolecids, and has more tail hooks than is the norm. Nevertheless, it is clearly a close relative of "Palaeoscolex" and "Wronascolex". As with the co-occurring Burgess Shale worm "Ancalagon", its name is derived from one of J. R. R. Tolkien's fictional dragons, in this case Scatha.