Have you ever marveled at the intricate patterns on a seashell?
Deep beneath the waves, a creature called a sea pen lives a life mirrored in this delicate armor.
These colony-forming creatures create elaborate, feather-like structures resembling calligraphy brushes, adorning the ocean floor. Just as the spiral array in a seashell mesmerizes us, the sea pen’s plume-like body captivates the ocean depths with its own mesmerizing symphony of form and function.

Prompt:
What seemingly ordinary object has a unique natural counterpart found exclusively in the depths of the ocean?