Fresh kelp has a layer of fine hair on its surface and can be eaten. If it is white Mao Mao, it can't be eaten, because kelp has gone bad. Dry kelp should distinguish whether kelp is moldy or not. In fact, there is a big difference between moldy and hoarfrost, and the moldy kelp will have a musty smell, which is easy to distinguish, so don't eat moldy or hairy kelp, because moldy kelp has bred fungi and is harmful to human body, even if it is washed off.