Researchers have described a new species of the enigmatic marine worm Xenoturbella, named Xenoturbella japonica. Two specimens of this new species were dredged from the seafloor of the western Pacific. These primitive worms, lacking a centralized nervous system, kidneys, and anus, are important for understanding the early evolution of the Bilateria. MicroCT scanning revealed previously unknown structures, and molecular genomic analysis suggested that features of this species may be ancestral to Xenoturbella. This newly identified species is promising for further research on early bilaterian evolution.