A curio is a small object that’s unusual, novel, or interesting, typically one that’s part of a collection of other such objects.
A curio can also be called a curiosity, and in fact it’s a shortening of that word. In a curio collection, there is often a variety of objects. The requirement for an item’s addition to the collection is usually just that it has to be curious, meaning that it arouses curiosity or is interesting in some way.