Undaria pinnatifida and Auricularia auricula belong to algae, but they are not the same thing. Auricularia auricula grows in the deep sea and belongs to red algae plants. The algae bodies cross irregularly, a bit like auricularia auricula. It's rare. You can only see it when you go out to sea in June and July, and it's difficult to collect it. Undaria pinnatifida is a kind of edible economic seaweed, which is widely cultivated.

Undaria pinnatifida belongs to laminariales of Phaeophyta and Auricularia belongs to Auricularia of Rhodophyta. Undaria pinnatifida leaves are green, pinnately lobed and thinner than kelp, which looks like a broken sunflower fan and nepotism. Auricularia auricula looks like Auricularia auricula, with reddish brown, yellow-green or yellowish brown color, wide membranous leaves, leathery or soft texture, forked leaves, antlers-like appearance and narrow base.