1. If you think algae are just plants living in water, think again. The mostly aquatic organisms produce oxygen through photosynthesis, though they lack many of the other defining traits of plants, including roots and leaves.
2. Algae can range from 100-foot-long giant kelp to several varieties of microbes called cyanobacteria, also known as blue-green algae.
3. Usually associated with dangerous algal blooms that can sicken humans and animals, these tough little microbes can also live in hot springs, under rocks in arid deserts and even under Antarctic ice.
