Get the green player to dig through the earth two spaces above the bouncy ball in the bottom - left of the level, but not the earth directly above it.
Move the green player to below the bomb in the top - left of the pile of bombs, and the blue player to one space to the right of the bomb.
Push both players left at the same time twice. Get the green player to shuffle right then left. Push the bomb left until it destroys the earth above the bouncy ball and frees it.
Move the blue player to one space right of the topmost bomb in the pile, and the green player to where they were before with the last bomb.
With the blue player, push the bomb left twice. Move both players left at the same time twice. Get the green player to shuffle right then left, then push the bomb left until it destroys the bouncy ball. Collect the crystal below where it used to be.
Bring the blue player in between two bombs. Push the right one right, making sure it doesn't destroy the sticky ball, and the left one left. Repeat this with the two bombs at the bottom. Collect the three now - accessible crystals.
Take either player to the top room. Dig through the earth below the rock, then go left twice. Collect all three crystals around the rock next to the right wall.
Now for some fun - Collect the earth under the bomb and go right once! After all the balls fall in the holes, collect the last crystal.