For the brain I decided to take a negative/positive space approach. Many of the brains seemed to have voids and holes, and I did my best to mark those as definite land marks. I also started marking what I called “arms” though I'm not sure if this was such a good idea as it was really hard to determine what should (and shouldn't be considered an arm). I also added points along the perimeter to help keep the shape, as I noticed from the faces that not doing this could give fairly disproportioned heads. Here is my brain atlas: