The iron core of Carlea is less active, producing a magnetic field, albeit somewhat weak. The lower flow also means there is no plate tectonic activity. Earlier in its history, there was far greater activity, bringing heavy metals to the surface. Since the crust froze, the nutrients and materials have remained stable.
Life evolved almost immediately in the oxygen depleted, storm ridden salted oceans, lightning initiating the reactions creating amino acids and other simple biologic monomers. Chemosynthesis consumed poisons in the atmosphere, followed by photosynthesis which filled the skies with oxygen. After the heavy rains created by comets, and the heavy bombardment of failed planetoids, life flourished in the shallow seas that covered the planet.
Bacteria-like life was followed by eukaryotic-like life, both encased by cell walls that acted as shields against the somewhat more intense radiation that penetrates the weaker magnetic field. One driver of evolution was the widespread use of plasmids, loops of DNA that rapidly transfer between individuals. Whereas eukaryotes as we know it do not use this mechanism, the more advanced cells of Carlea evolved to continue utilizing these, enabling the widespread sharing of genetic material between species.
This was to guide the remainder of evolution for the planet, since species as a whole were not to be in direct competition with one another. One species would benefit from its neighbor, leading to multiple species occupying the same niche. Asexual and then sexual reproduction for all species are controlled by ‘braking’ proteins that limit offspring by available resources, which prevents population collapses as seen on most other planets.
Plants rapidly diversified, from algae to simple floating plants that sail the high seas. The shallow oceans receive light on the bottom, where even the dim rays toward the red end of the visible light spectrum allow the growth of broad-leafed plants that are grey in color, and cover the ocean bottom. Scant light power has led to great biodiversity across the ocean floors, as the plants have evolved creative ways to overcome these limitations, with leaves growing to several meters in size across, catching not only light, but the rain of dead material from above, and eating them like animals.
Coral reefs are everywhere, and each riot of coral is capable of photosynthesis and consumption of plant and animal material. This resulted from the widespread sharing of plasmids, even among advanced individuals.
On land, there are swamps, deserts, and rainforests, all stricken by low soil quality and intense radiation from above. Plants and animals alike have cellular structures carrying cell walls forming incomplete shields that still allow flexibility and movement.
Rainforests hold colossal trees over 400 meters tall. Their height does not compare to their depth, boasting roots that penetrate a kilometer into the crust, the roots capable of surviving a dense and hot crust interior. These anchors serve primarily as miners, transporting heavy metals and minerals from the crust to the surface. This bonanza of nutrients has led to impossibly dense forests. Smaller plants have used the same plasmids that code for the roots of the trees, with some grasses and squat shrubs also having kilometer long root systems that grow slowly but steadily, inexorably exploring the interior for every possible nutrient.
Over time, the trees have exhausted their attempts to spread to new biomes, and finally settled on expending excess energy creating ultralight spores that are shot into space in bubbles of hydrogen and helium. These are capable of surviving a vacuum near zero Kelvin.
Animal life is similarly diverse, with sea life of squid and fish that form the bulk of the complex food web. Most animals are slow growing and developing. The infrequent development of a species that is more aggressive and competitive has invariably been ‘infected’ by plasmids that brake growth and development, and any evolutionary arms race returns to the status quo.