Royal Icing Cockle Shells

This is yet another one of those projects that I thought of while doing something completely unrelated to cake decorating; probably driving or doing dishes. I was thinking about the curved petal tips used for piping violets and, well, not much else. It seemed to me they might be the right shape to pipe shells; after looking around on Wikipedia, I figured the exact shell I had in mind was the cockle, a "group of (mostly) small, edible, saltwater clams." Here's all I needed; medium consistency royal icing in a bag fitted with a #61 curved petal tip, parchment paper squares, a flower nail, and a glue stick.

First, stick a parchment square to the nail with a dab from the glue stick.

 Here's a close-up of the tip. As you can see, one side is wider than the other.

 Hold the wide side in the center of the nail, almost perpendicular to the surface. As you begin piping, keep the wide side in the center and rotate the narrow side clockwise while pulsing the tip up and down to form ridges.

 When the shell is the right size and shape, stop piping and draw the tip toward you. You might need to tap any rough edges into place with a fingertip or back of your fingernail; touch your finger to a dusting pouch filled with a 50/50 mix of powdered sugar and cornstarch, if need be.

 Here's another view from the other side:

 Here's another, slightly wider, shell…

 …and another view of it.

 The shells turned out very tiny, and they were made with the largest curved petal tip I own. They'd be ideal any time a tiny decoration is required (like for petits fours, mini cupcakes or cake pops), and could definitely be piped with a striped bag or dusted with Pearl Dust.