ET looks like green moss. Boffins can claim to have finally found alien life after the plant spent nine months growing on the outside of the International Space Station in orbit 250 miles above Earth.

The curious minds at What If land on Proxima Centauri b and explore its alien environment, revealing climate, terrain, and habitability.

Introduction: Nonnative species in the world / David Pimentel -- The impacts of alien plants in Australia / Richard H. Groves -- Environmental and economic costs of invertebrate invasions in Australia ...