A Yeerk is a parasite that takes over the body of another being by way of infestation through the ear canal. It resembles a small, grey-green slug about six inches long.

After the process of infestation, the Yeerk flattens itself into what has been described as "hammered-out gum" and sinks into all of the cracks and crevices of the brain. From there, all control is submitted involuntarily to the Yeerk (however, the host may fight and very rarely win). At this point, the host has no control over itself, no secrets, and no privacy. The Yeerk can even play with the memories of its former host. Although control can be returned to the host by the Yeerk, this does not occur often as most Yeerks prefer their parasitic relationship to a symbiotic one.

you're making brainslugging trippy art... when next piece is out we'll see what's going on...

And Yeerk makes you think you have no Yeerk in ya brains