Thysanocardia procera is a marine invertebrate belonging to the phylum Sipuncula, the peanut worms.

In a revision of Thysanocardia in 1983, the subgenus was elevated to full genus rank, with only three species being retained, T procera, a North Atlantic species, the widely distributed T. catherinae, and T. nigra with a north Pacific distribution.

The introvert is several times as long as the trunk when extended, and the whole animal may reach a length of 50 or 60 mm (2.0 or 2.4 in).

A further six to ten short tentacles surrounding the nuchal organ, which has two lobes separated by a groove.

It also occurs in the northwestern Atlantic between about 34°N and 40°N, and has been reported from California, but its precise distribution is unclear.