Osmiridia

Osmiridia is a terrestrial planet roughly twice the size of Earth, but it is made of only light silicates and small amounts of aluminium oxide & has no iron core, giving it only 1.14 times earth's gravity.

Life
Life evolved on Osmiridia roughly 6 b.y.a., after a very large comet containing self replicating organic molecules (much like the red rain of Kerala) crashed into soft clay near the equator. Life then flourished creating the most species on a single planet in the entire Milky Way Galaxy. 7 sentient sub-species co-exist on Osmiridia.

Sentient Life
7 sentient sub-species co-exist on Osmiridia. Even though they are aware of their genetic differences they treat each other as equals, and since they are all fully genetically compatible with one another they even marry each other.They are currently in the Steel Age. They co-exist much like how Homo Sapiens once co-existed with Homo Neanderthalis. They are members of the Tri-Star Conferderation.