It possessed a pair of branching tentacles and a tough but flexible body that curved helically to the right like a ram's horn and was divided into at least 13 segments.

A flexible, extensible stolon emerged from the body at about the ninth segment and secured the animal to the sea floor, often by attaching to the sponge Vauxia.

[5] A mouth opened between the tentacles, leading internally to a pharynx, a large lentil-shaped stomach, a narrower straight intestine, and an anus at the end of the "tail."

Structures on the back of the head have been noted as potential pharyngeal pores, which suggests a relationship with early echinoderms.

[1] The six specimens of Herpetogaster are known from the Greater Phyllopod bed, where they comprise less than 0.01% of the community.