The genus is closely related to Anabarella, with which it bears many morphological similarities, including a laminar internal shell microstructure said to connect it with the early bivalves Fordilla and Pojetaia.

[1] The type specimen was found in a fossil-filled boulder collected by Thomas Augustus Watson, the assistant of Alexander Graham Bell who received the first-ever telephone call.

Grabau initially interpreted Watsonella as a heteropod gastropod similar to the modern genus Carinaria.

[4] In 1988, Martin Kerber hesitantly synonymized Heraultipegma and Watsonella, and Ed Landing affirmed their synonymy in 1989.

[8] Unlike rostroconchs, Watsonella lacked a pegma, although the curvature of the shell may have served a functionally similar role.

The outer layer was composed of regular, tightly-packed prismatic units that were oriented perpendicular to the shell wall.

[12] The shell microstructure is very similar between Anabarella, Watsonella, and the early bivalves Fordilla and Pojetaia.

[11] A phylogenetic analysis conducted in 2000 by a team of researchers led by J. G. Carter recovered Watsonella as more closely related to bivalves than rostroconchs.

They suggested that Watsonella should be reinterpreted as stem-group members of Diasoma, the clade uniting bivalves and scaphopods.