It’s called hippocampus, but I like to call it “the ear of the brain”. First, it doesn’t look anything like an hippocampus, and on top of that it cannot swim; sorry they cannot swim –yes we have two of them, one on each side of our brain. Two, it does look like the helix of the outer ear. Three, it listens to everything around us; yes, sorry, they listen to everything around us, and they keeps track of it. The hippocampus is a key element in the formation of new memories either experienced events (episodic or autobiographic memory) or spatial memories. Like our ears, hippocampuses are part of our own navigation system, our own GPS. I told you… they are the ears of the brain.
A Fish on a Hill 