Am doing a lighthouse cake and have noticed everyone using little pebbles i am assuming they are edible..what exactly are they and where do u get them? thanks, Dawn

They are probably candy rocks. You can find them online. Or possibly fondant rolled into rock shape.

Yes, you can buy candy rocks they are a bit expensive. I made a hiking cake in Nov. I made rocks out of fondant. they didn't look too bad.
Actually friend was looking through my pic's on my camera one day and when she came upon this cake she said. Hey, where the %^$# were you when you took this pic , who's they guy are where were you hiking?
LOL. I said it's a cake. She didn't believe me til I zoomed on the pic.
So fondant rocks CAN be made to look real. or better try using gumpaste
M