Without the size restriction of a shell, red algae can form larger plants, and spread throughout the ocean.

Many are widely spread, small (tens of centimeters long) , red seaweeds, but some grow much larger over substantial areas and have become human food crops.

In Japan, nori is used to make sushi and related products. It has been eaten for centuries and farmed for at least three hundred years.

In Britain and Ireland, Dulse and Laver have been used to make local foodstuffs for generations.