It was found in the Maotianshan Shales, which date to roughly 518 mya.

[1][2] From the latin vetus (old), plus "cystidae" referencing the bag-like shape.

The specific name is from the latin catena, meaning chain, as a pun on the fossil as a missing link.

[3] Vetulocystis is distinguished from Dianchicystis by a widening, rather than tapering, "tail" (posterior section).

[3] [citation needed] Dianchicystis Vetulocystis Thylacocercus