free living

Scientists have identified around 400 species of free-living amoebae, but only six are known to cause disease in humans - including Naegleria fowleri and Acanthamoeba, both of which can infect the brain.

It’s also a parasite — because who needs to be free-living when you’re this fabulous?

Nematodes are among the planet's most abundant animals, "free-living" in water, soil and the Earth's crust in addition to parasitizing a large collection of plant and animal species.

Photosynthesis takes place inside chloroplasts, small compartments within plant cells that contain their own genome, reflecting their past as free-living photosynthetic bacteria before they were engulfed and co-opted by plants.

The lifecycle of soil-transmitted helminths has two phases -- a free-living stage as eggs and larvae in the environment and an adult stage inside the host.