Rhombocorniculum is a species of small shelly fossil comprising twisted ornamented cones.

[1] The structure of its inner layer suggests that its phosphatic fibres formed within a flexible organic matrix.

[3] Three species are recognized — in stratigraphic succession: R. insolutum, R. cancellatum (=R.

[3] Hinz (1987) considers insolutum to fall within the variability seen in cancellatum.

Based on details of the ornament and construction, Rhombocorniculum is interpreted as the spines of a Hallucigenia-like lobopodian worm.