Neopyropia katadae belongs to a group of red algae which grow in a sheet-like form, often called 'laver' or 'nori'. Gametophytic blades are round, oval, or elongated, attached to a short cord-like stem and a disk-shaped holdfast. The blades are smooth in rounder forms, but ruffled when they are more elongated. The blades are 60 to 20 mm wide, and 30 to 160 mm long. The blades are monecious, having male gametangia (reproductive tissue) on one side of the blade, and female on the other,, This algae grow as an epiphyte on another red alga Chondrus crispus, called 'Irish Moss', and sometimes harvested as food. Neopyropia katadae is native to Pacific Russia, China, Korea, and Japan. It is rare, known from 4 sites on Cape Cod and Rhode Island. It grows in the low intertidal and shallow subtidal zones Possible vectors include hull fouling of ships and unsuccessful plantings of Pacific Oysters.