Vesicle pisces

A vesicle pisces is the name that author Philip K. Dick gave to a symbol he saw (on February 2, 1974) on the necklace of a delivery woman.

PKD was probably conflating the names of two related symbols, the ichthys consisting of two intersecting arcs resembling the profile of a fish, and was used by the early Christians as a secret symbol, and the vesica piscis, from the centre of which the ichthys symbol can be drawn.

Scott Barbacki speculates that P.K.D. may have interpreted these arcs as a portion of DNA's double helix.