Prototypes are actually used to build objects, and they will usually need information from you before they can build the actual object.  So, in a strict sense, Prototypes aren't objects.  Not quite.  Once they have the data we say that they have been instantiated ... that is, an instance of the prototype has been created, and will now work like any other object.

Importantly, an instantiated prototype can be saved to a decoration set with all of its instantiating information, so when other people view it (or you come back to it later on, even after clearing your cache or whatever) they will see the instantiated object.

If you want to change the information that you instantiated the prototype with you can open the Properties window by double-clicking on the object.