Egg Cockle is called "the aristocrat of the sea" which is harvested mainly in the Chungcheongnam-do region of Korea. In Korean, it is called a "bird clam", and it is named because the meat inside the shellfish resembles a bird's beak. It is known as a specialty of Namdang Port, Hongseong-gun, as it is in season from January to February (cold winter) in the West Sea tidal flat.

The ink is a dark reddish brown. It is designed to capture the red tint like the color of Egg Cockle's shell. Unlike many dark inks that often appear black when written, this ink, when used with a fountain pen, displays the true purplish-brown color effectively.