Multicelluar organisms exist but they aren't "fluid" like I described. It's not like animals will spontaneously combine into a single organism. Some plants can

Multicelluar organisms exist but they aren't "fluid" like I described. It's not like animals will spontaneously combine into a single organism. Some plants can sort of do this, like bamboo forests. But they don't have a lot of specialization like animals do, with different organs and stuff.