Algae is something I am familiar with. On a daily basis I drink the microscopic type of algae, Spirulina, and so I looked forward to trying it's macroscopic cousin in the form of seaweed or Carrageen moss (Chondrus Crispus). Also known as Irish moss, it is a dark purplish seaweed and is abundantly found growing on the rocks in the lower part of the Irish seashore, Carraig being Gaelic for rock.
The seaweed is dried out and bleached in the sun after being collected at low tide during the summer. After purchase the seaweed is usually soaked for about 15 mins to half an hour to rehydrate and then washed thoroughly under cold running water to remove dirt and much of the salt.
Carrageen moss is high in vitamins and minerals such as iodine, vitamin A, vitamin B12 and others but also has a range of other effects such as being an antiseptic, digestive aid, blood thinner and it encourages phlegm to be coughed up while soothing dry mucous membranes. The latter explaining why it is traditionally used in Ireland for com batting chesty coughs or chest infections.
As well as it's traditional medicinal usage, it also has a traditional culinary usage in that it is a very good thickening agent for soups, stews and in making jellies.