So named because it resembles a seahorse, I once heard.

"Memory, Learning, and Emotion: the Hippocampus

Emotion and memory are very closely related. You know this from your experience. Go to a party, meet a bunch of new people. Which faces are you going to remember? The woman who made you laugh, the man who made you feel embarrassed, and your new boss -- the ones who had an emotional impact.

So perhaps you would not be surprised to learn that the a portion of the emotion system of the brain (the "limbic system") is in charge of transferring information into memory. From years of experiments and surgical experience, we now know that the main location for this transfer is a portion of the temporal lobe called the hippocampus."
http://psycheducation.org/emotion/hippocampus.htm