It's entertaining to learn the names of groups of animals---for instance, a clowder of cats, a parliament of owls---as well as the familiar ones, like a pod of whales or a pride of lions. Hedgehogs come in arrays or prickles---and baby hedgehogs are called hoglets.
Here is a Little Free Library, beautifully decorated, with many books. One looks a little different. Could that be a cache? And could hedgehogs be a hint?