Dr. Atsuko Nishigaki and their research team from Toho University, discovered that the marine worm Marphysa sp. E, an annelid living in the tidal flat sediments of Tokyo Bay, rapidly decreased the concentration of polycyclic aromatic hydrocarbons (PAHs), which are carcinogenic environmental pollutants, by ingesting and excreting organic-rich reduced mud containing high concentrations of PAHs. The PAH concentration was halved within two hours.