Complete "Fuxianhuia" specimens are approximately 4 centimetres long. The anterior of "Fuxianhuia" is encased in an oval sclerite, from which two stalked eyes emerge. Inserting directly behind this sclerite, on the head shield proper, are two stout antennae. When the head of "Fuxianhuia" was originally described, two additional head appendages, the "sub-chelate" pair were also described. These are geniculate, backward-pointing appendages that lie in a highly stereotypical position (i.e., their position does not vary much from one specimen to another). Partly because of this, and partly because of their rather indistinct morphology, their status as appendages has been questioned. Indeed, on the grounds that these structures seem to lie between two cuticular layers, Waloszek and colleagues have suggested that they are not appendages at all, but rather gut diverticula; a reassignment that has however not been universally accepted. Ventrally, a large plate has been interpreted as a hypostome.