I hope I'm not boring anybody with all these little sea creatures; one seems to inspire another! I piped this tiny oyster with the Ateco tip #98, which is scalloped with grooves on the outer side.
I stuck a square of parchment paper to a flower nail with a dab from a glue stick. I held the tip against the paper and piped a shell shape by keeping one side of the tip still and moving the other side around in a clockwise motion while vibrating the tip to create ridges.
dusting pouch; this will be the side on the bottom: