Ercaicunia is genus of bivalved Cambrian arthropod from the Chengjiang biota of Yunnan, China. It contains a single species, E. multinodosa that was described by Luo et al. in 1999. The total length of the body ranges from 8 to 11 millimetres (0.31 to 0.43 in). The bivalved carapace covered about a third of the total body-length, and has up to six serrations on its forward edge. Specimens were CT scanned in 2019, which revealed it to be a stem-group crustacean. Other subsequent studies have recovered it as a member of Hymenocarina, which contains other bivalved Cambrian arthropods.