Pond scum could be used to feed the world if it is used as a protein substitute in meals, a Cambridge University professor has said.
While spirulina and chlorella, which are micro-algaes that form on top of water, are well known to health fanatics and have been eaten in space by Nasa astronauts, scientists hope they could become more mainstream in the future.
This is because they can be grown in urban environments and do not require high-quality agricultural land to grow, so could feed a growing population, especially if climate change renders some farmland unusable.
The small algae particles contain iron, B vitamins and protein along with other vitamins and minerals commonly found in meat, fish, eggs and dairy. The versatile powder can also be used as a supplement in bread, and instead of eggs in cakes and other baked goods.
Some chefs are even trying to turn it into fake "meat" - IKEA has commissioned Danish chef Simon Perez to make a version of their meatballs out of spirulina. He said he has managed to make it "taste the same" as meat, but that he is still working on the texture.
However, nutritionists have warned that as of yet, some of the nutrients are not bio-available, meaning that the body finds it more difficult to absorb than a non-vegan alternative.
Professor Alison Smith, the head of plant science at Cambridge told the BBC Food Programme that scientists are working to make the microalgae a viable alternative to other, more high-impact foods.
She said: "As the population of the world increases and the land that's available for agriculture is becoming stretched there's an interest in trying to boost production in other ways.
"We have to produce food that doesn't require high quality agricultural land.
"Algae and spirulina is grown in all sorts of locations in water. Even on your patio and on snow. One of the possibilities is to produce them in cities or towns as they don't need the open landscape to be grown."
She added that far from being a recent fad, cultures have been eating pond scum for some time, adding: "People have been eating algae for a very long time, there are reports from several hundred years ago of people in South America scooping spirulina out of ponds to supplement their diet."
Rhiannon Lambert, a Harley Street nutritionist warned health-conscious eaters should not immediately ditch meat and eggs for algae.
She said: "Spirulina is between 55 and 70 per cent protein by weight and does have a better amino acid profile than most plant based foods but that doesn't mean it's better than the animal based protein that we can get or soy or quinoa.
"It's an awful lot of powder to reach an adequate amount of protein."