Tiny and covered with spines, many of us wouldn't expect hedgehogs to make great pets. The truth of the matter is that, with proper care and a warm habitat, caring for a hedgehog can be a very rewarding experience. Their spines are defensive in nature, so there isn't a need to worry when they curl into a prickly ball. Curling into a ball is a common reaction of nervousness and fear for hedgehogs, especially when being introduced to new people. After a bit of time together, the animals typically become very affectionate toward their owners.
Apart from when feeling in danger, hedgehogs also love to curl into a ball when they are asleep. As you can see in this video, they look absolutely adorable when doing so.