1. Spines two per valve, elongated
  2. Frustules lightly silicified
  3. Numerous scale-like girdle bands

Acanthoceras is a solitary, planktonic genus. Cells are usually seen in girdle view, because of the numerous girdle bands and spines creating a large length to breadth ratio. This centric diatom appears somewhat rectangular in shape, with two spines, or setae, extending from each valve. Living cells contain four small, plate-like chloroplasts.

Populations of Acanthoceras form ephemeral summer blooms in shallow, eutrophic lakes and ponds in North America. The lightly silicified valves of this taxon are easily destroyed with standard diatom processing methods, and the genus is rarely recorded except in live material or burned-mount preparations. As with Urosolenia, Acanthoceras forms heavily silicified resting spores. These spores have a characteristic morphology and are often encountered in sediment cores.