Nesochthamalus possesses a partially calcareous saucer-shaped basis, and fused opercular plates which show no visible trace of former articulation.

[3]: 85 Opercular plates of Rehderella are distinctive in the scutum and tergum of each side fusing in young stages.

[2]: 327 [3]: 85 Soft part distinctions include card setae on cirri develop only after animal reaches a size of 5 mm.

[2]: 328  Caudal appendages are present, growing longer with age, up to 20 segments in large specimens.

[2]: 330  In this upper zone, dominance is shared by the gastropod Nodolittorina pyramidalis pascua, an algal grazer.