Paramecia manage to do quite a lot without any brains at all [1]. They do have microtubules though [2]. [1] https://www.ebiomedia.com/the-biology-classics-para

Paramecia manage to do quite a lot without any brains at all [1]. They do have microtubules though [2]. [1] https://www.ebiomedia.com/the-biology-classics-paramecium-behavior.html https://www.ebiomedia.com/the-biology-classics-paramecium-be... [2] http://www.ruf.rice.edu/~bioslabs/studies/invertebrates/microtubules.html http://www.ruf.rice.edu/~bioslabs/studies/invertebrates/micr...