Spinella cf. S. yassensis

A spiriferid brachiopod: a wing-shaped shell with a strong fold and furrow down the middle and fine ribbing across the valves. Inside, the animal carried a pair of spiral calcareous ribbons that supported the feeding organ.

Brachiopods are not molluscs. The two valves are top and bottom rather than left and right, so a brachiopod shell is symmetrical across the midline of each valve — the quickest way to tell one from a clam.

The type species of the genus, Spinella yassensis, was named from these very beds at Yass.