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.