Angelwing Shell Art on Canvas in a Black Bijou Frame.

Angelwings are also known as piddocks. Angelwing  shells have ridges or "teeth", which the resident snail uses to grind away at clay or soft rock to create tubular burrows. The shape of these burrows are due to the rotating motion of the Angelwing shell as the snail grinds the rock to make its home. The Angelwing snail stays in the burrow it tunnels for the entirety of its eight-year lifespan, with only its siphon exposed to take in water that it filters for food.

It is rare to find angelwings shells with both halves still intact.  Muscles fusing its valves together are weak and therefore when exposed to human touch, it closes and shatters. Some shell hunters dig up living clams and then place them into containers filled with water straightaway so they don't close up on themselves. 

If you are a conchologist (collector and student of shells) we would love to hear from you about how you would improve this description.