For Asteroxylon to appear in the cube, Baragwanathia needs to be around along with some area with little moisture along with a high cube temperature. Its birth temp range is very similar to Bargwanathia, so if the player has it already, Asteroxylon is close behind. After a bit of time with these conditions or by using a Seed of Mutation on Baragwanathia, Asteroxylon should appear.
During the story mode, it becomes available during the first episode: The Cube is born.
|←||No.003 Baragwanathia||Organisms||No.005 Cyclomedusa||→|