How to split an object into two individual sub-objects?

This is part of a project to have an avatar’s eyes track a pencil. Since the avatar was imported from MakeHuman, the eyes are in one unit. I want this object split in half, so each eye can be it’s own object, but I haven’t found any answers so far. So, what do I do?

You won’t be able to do that within Unity. Try using Blender.