Spirulina is a blue-green algae that is supposed to have some amazing health effects when you eat it. It is sometimes referred to as Superfood when sold in a dried form. This article describes some of the potential benefits but also contains a word of caution about the hype:
The interesting thing about Spirulina is that it is easy to grow it at home, for example in an aquarium. All you need is a a hydroponic growing medium, some live spirulina starter and a few pieces of common aquarium equipment like a heater and a bubbler.
This video shows you how to harvest grow Spirulina from an aquarium:
See also: - Grow your own Spirulina