With favorable space at a premium, and intense competition and predation, gathering is a way of life in the intertidal.
Clik here to view.

intertidal scene
Clik here to view.

Clik here to view.

***
Note: Little brown barnacles, Chthamalus dalli, featured in the image at the top of this post, don’t pack as tightly as some other barnacles, but they still gather in favorable spaces.
Image may be NSFW.
Clik here to view.

Clik here to view.
