Biology analogies

[Comet striker]

Don't know if this is supposed to go here. Don't know if this should be a thing but either way:
This thread's purpose to make analogies for bio stuff to make it more easier to understand. I'll start by example:
The Golgi apparatus is the postal service of the cell.
etc hopefully you get the idea
Just to make sure, analogies on this thread arent definitions and you really shouldnt try and use these in a test lmfao