Hedgehog

If you have seen a hedgehog then you know that they are almost completely covered with spines and can roll up into a ball to protect themselves. There are currently 17 different species of hedgehog living in Europe, Africa, Asia, and New Zealand. However, the hedgehogs in New Zealand were introduced to the area and are not indigenous there.

http://www.treehugger.com/files/2009/01/sonic-hedgehog-11-year-old-change-pet-laws-kansas.php

Most hedgehogs are nocturnal and are most active during the night. This makes it very rare to see a hedgehog in the wild. Small and agile, a hedgehog is difficult to spot for humans in the night, especially if they live in a dense forest. It is also challenging to spot a hedgehog during the day when they are sleeping. Depending on the habitat a hedgehog lives in, it may sleep in a bush, in the grass, under a rock, or in a hole. No matter where a hedgehog lives, they generally tend to dig dens for shelter.

http://animalpetdoctor.homestead.com/hedgehogs.html

Hedgehogs have been classified as being insectivores, which means they eat only insects. However, once again, depending on the area that a hedgehog lives in, they can eat insects, frogs, snails, snakes, mushrooms, grass roots, and berries. In this sense, hedgehogs could be seen as omnivores.

http://www.buzzfeed.com/zacharyj/swimming-hedgehog-4aj

When they feel threatened, hedgehogs are able to curl up into a ball and protrude their spines outward. However, some predators have found ways to force the hedgehogs out of their protective "shell". For example, some foxes have been observed dropping a hedgehog into the water, which makes the hedgehog unroll and swim. Once the hedgehog is exposed, the fox will go for the kill by biting at the hedgehog's head.

I personally think that hedgehogs are very unique little animals. There aren't many animals that can roll up into a ball for protection. I think the only other animal that has that ability would be the armadillo. There are probably others, but at the moment I can't think of any more. I also like how hedgehogs look like a mixture of a mouse, hamster, and porqupine.