So this is a bit of a different one. A piece that  zephra did a while back.

This isn't actually Sai himself, but a prehistoric predecessor far back before history. The world doesn't have much in the way of colour, lending to the fact that the vegetation doesn't use chlorophyll to conduct photosynthesis. Instead they use pockets of nanomachines, which gives them a dark grey, often black colouration. Given that grass hasn't evolved on the planet, the undergrowth is covered in semi-transparent fleshy sails that glow in different colour whenever they move. This luminescence comes from a little reservoir of nanites that the organisms use to attract animals to spread their spores.