Endosymbiosis?

Some organelles are available to purchase using Mutation Points from the start of the game (such as mitochondria or flagella), while others must first be assimilated by endocytosis.

Chloroplasts, for example, are found throughout the environment as free-living cyanobacteria, and by engulfing them (an engulfing edge is not necessary for bacterial assimilation, only eukaryotic) the player might gain a chloroplast within their body. The chance of this happening is minimal (~1 in 100), and the player is not granted access to chloroplasts as a usable organelle in the editor until they have engulfed one. Once a cyanobacterium does survive on engulfment, the player receives one chloroplast for free (only in their individual until the next editor session, but in their whole species thereafter) and can place new ones in the editor in exchange for Mutation Points. Endocytosis is only possible if the player’s cytoskeletal structure has space for the new organelle – that is, they must have at least enough blank cytoplasm in their cell’s hexagonal arrangement for the organelle to be placed if it were in the editor.