On clubpenguin how do you find the rare treasure in aqua grabber in clam waters?

In aqua grabber you go down to the huge clam and get a rock that is the same shape as the pearl. Grab the rock and put it into the clam's mouth and then grab the pearl!!

and to find the rock with a star...go to a small clam and wait above it until it sleeps.

then once its mouth is all the way open you can GRAB it very quickly and you will automaticaly have it.