How is a living being/lifeform defined in Buddhism?

As asked in the question, what are the characteristics by which a thing is classified as 'living being' or 'non-living' ? How is a lifeform defined in Buddhism, I mean, like how humans consider themselves as living beings due to various facts such as: their experience in this world due to consciousness, their actions (kamma), etc. If lifeform is defined as something that has consciousness and capable of producing kamma, what things are concious? Is a plant a living being/conscious? Is a **stone** living being/conscious? Is the universe conscious? Is everything a lifeform in some way? Is rebirth possible only as a lifeform? (I mean, by rebirth, just a transfer of consciousness/experience subject to different conditions. Please correct me if I'm wrong) Can our next rebirth be as a stone/whatever, other than the 5 predefined possibilities (human, god, ghost, animal, hell) in Buddhism? I'd be glad if all the questions are addressed :)