Bizarre Alien Reproduction: …are you sure you really want to know?
Well, first, if it’s done on Earth, by anyone, it’s probably used somewhere. Mere external fertilization, et. al., is relatively mundane. The temísi, say, are quite straightforwardly parthenogenic. For exotic – well, then we’re getting into how the vlcefc reproduce by having their motiles spin a new brain-web, something that any number from one up can do together. Or the esseli literally building the next generation in their gene-labs. Or the codramaju simply coming together as X individuals and coming apart as X+n individuals, any of whom may contain various different bits of the minds of the original X. Or…
And that’s before people come up with clever ideas like bigenetic organisms, in which – say, a plant and insect are mutually engineered so that the plant can grow insect eggs and the insect lay plant seeds, thus enabling them to mutually spread each other in early-stage ecopoesis, and contribute to a more stable ecological web overall.