What you need:
A-line cotton or jersey-knit nightgown, approximately 210 aluminum cupcake liners, one large roll of green corrugated paper, green glitter glue, starfish, glue gun, barrette or hair comb.
Open the side seams of the nightgown 7 1/2 inch up from the bottom. To accommodate the tail fin, fold opened seams in on an angle so that the bottom of the nightgown is now 11 1/2 inch wide. Starting at the bottom front of the nightgown, overlap and glue a row of flattened cupcake liners. Repeat until entire front side is covered. Turn over, and repeat on the back. When finished, add a final layer to each side, just above the 7 1/2 inch opening. Enlarge shell top and tail fin templates as needed, and cut out. Trace onto green corrugated paper, and cut out. Decorate with glitter glue. Use a glue gun to attach to nightgown.
To make starfish barrette:
Glue a store-bought starfish to a barrette or hair comb, and place in hair.