This is the nudibrach Hermissenda crassicornis. While it may not look like much, when I look at it, I think 'smart'. H. crassicornis has often been used as a model animal as it is a great thing to study if you want to learn how memories are formed. They have a very simple nervous system, simplified to the point where every neuron has been mapped and named. Additionally, they can be conditioned to respond in certain ways when presented with a stimulus (much like Pavolv's dogs). Put that together with the ability to follow impulse along the nervous system, and you can 'see' how the slug reacts normally to a stimulus, then see how the route changes after you condition them. They've actually found out where memories are stored in these guys! If you want to learn more about learning check out Blackwell, 2006 for a review on the subject.