An antibiotic is obtained from a diatom Nitzschia palea, which is effective against Escherichia coli.

Funori is a sizing agent and a glue obtained from Gloiopeltis furcata. It is similar to agar-agar and is used in cosmetic industry.

Chara is used to overcome calcium deficiency in the fields. Thus, a rice field deficit in calcium would most probably be helped by addition of chara.

Carrageenin is used as a clearing agent in beer production. It is a carbohydrate mucilage extracted from red alga.

No antibiotic is obtained from cyanophyta.

Laminaria, Sargassum, Fucus and Ascophyllum are used as fodder for animals. They are especially used in coastal countries for their richness of nutrients.

Porphyra is used for making Japanese rice delicacy Sushi. It is known as Nori in Japan.

Lyngby is responsible for causing skin diseases in humans.

Rhodochytrium spilanthidis is found as a parasite on ambrosia leaves. It destroys phloem of the host.

Odonthalia corymbifera is a rich source of bromine. It is about 6% of dry weight.

Synchococcus algae have rapid rate of photosynthesis and are used to utilise all CO₂ released by astronauts in long-distance space travel.

Alginates obtained from brown algae are used for making dental impressions of teeth. Alginates are both skin and food safe.

Vitamin B12 is absent in spirulina and spirulina supplements are not considered to be a reliable source of vitamin B12, as they contain predominantly pseudovitamin B12, which is biologically inactive in humans.

Rhodymenia palmata is a red alga producing fucosterol. Fucosterol is the base material for the manufacture of sexual hormones and steroid synthesis.

Genus Ulva is referred to as sea lettuce. It has very long blades and is used in food.