title: Rhombocorniculum
text: # Rhombocorniculum
  
  Rhombocorniculum is a species of small shelly fossil comprising twisted ornamented cones. It has been described from the Comely limestone and elsewhere. R. cancellatum straddles the Atdabanian/Botomian boundary. The structure of its inner layer suggests that its phosphatic fibres formed within a flexible organic matrix.
  
  ## Taxonomy
  
  Three species are recognized — in stratigraphic succession: R. insolutum, R. cancellatum (=R. walliseri), and R. spinosus (=Rushtonites spinosus). Landing (1995) refers R. insolutum to the strictocorniculids, along with Rushtonites. Hinz (1987) considers insolutum to fall within the variability seen in cancellatum.
  
  ## Affinity
  
  Based on details of the ornament and construction, Rhombocorniculum is interpreted as the spines of a Hallucigenia-like lobopodian worm.
  
  