The Dink Network

So the statue says ask the gravedigger... grave digger says ask the guy in plaid... plaid guy says ask waterfall girl... waterfall girl says something about covering an orb with a rock in a hidden cave (how is that related to watercan?) Anyway, I eventually found (a) hidden cave with a bunch of barrels with hearts, I don't seem to be able to interact with any of the rocks to find their orbs, or a watercan for that matter. What's the secret here?