I know I got it right for the F4A challenge - Birthday card.
Not so sure about the MIX challenge - my two seahorses are identical, one smaller than the other. They are not nested, but they are the same shape exactly. Sorry, if it doesn't qualify. Anyway........
I covered the water color paper with gesso, dried, and covered with Brusho crystals, misted with water, then dried again. Cut my card base and cut the water color background to fit the base. Stamped the coral with Versamark, sprinkled EP over it and heat embossed, then fussy cut around the outside edge. Die cut the two different size seahorses, 5 fish, a starfish and seaweed. Added Stickles dots to the fish and starfish and a line of Stickles along the Seahorses spines. Black dot for eyes. Assembled.