Rocky world
A different world, naturally. We’re talking 3.64ms^-2 gravity(Rather low), a nearly pure stone world, with the entirety of its heat coming from its centre as it has no sun. Since it is rather small and not particularly dense, this heat will probably only last a couple thousand more years, as the planet itself hurtles along through the void that is space.
This world would be kind of boring without life though, right? Well lucky us, there is life. but it is nothing like life on our planet.
There are different species of stone-like-creatures, that roll around over the planet. They slowly absorb the land they end up on for sustenance, and to grow, while excreting the sediment they ate that they don’t want.
These creatures randomly mutate within themselves, changing their existence on a fundamental level. If a change works, it lives, but if a change doesn't work, those mutations die off, and the rest continue.
Normally, this would result in large cancer rates, but for this race, the cancer cells are just more stones, so they get excreted instead. This is also how they all multiply.
Over time, one rock might end up absorbing nearly the entire world without dying due to different causes, resulting in the world being a giant lifeform for a while. This doesn't last long though, because as they get bigger, cancerous cells become more common, resulting in it excreting so much body mass, it can't be counted as the world itself anymore.
Oh, and the energy for this life and everything else comes from the magma below. Unfortunately, none of the life so far has managed to utilise it as anything more than a heat source, unlike what plants did with our sun.
This is the general layout of that small world, a world that periodically becomes a large lifeform, and a world doomed to die in a few thousand years. Even if some random intelligent life form was to come across it, they probably wouldn't even consider it to be alive. But there is no denying its existence, as a world of life, a world that could result in some amazing things, if it lasts long enough.
#sci-fi