Imperial County, California, US
These tiny Semibalanus cariosus or Thatched Acorn Barnacles were filter feeding with their little cirri along the edge of the dock at the marina.
These small Balanus crenatus or Crenate Barnacles were covering pipes and pilings in the marina.
Taken from dorsal fin of smooth dogfish, Mustelus canis. Parasitic copepods are not uncommon on the fins of local sharks. This pair seem more colorful than Im used to seeing. Could be Alebion glaber. Another example of where I wish I could link two observations via an association.
Acorn Barnacles (Balanus sp.) at Sungei Serangoon ©Tan KH
the wavy feather-like plume, not the substrate in the foreground
On conch traps.
Found these on the same piece of drift kelp as Triopha maculata. I've included a photo of the carina which is laterally expanded like whale flukes, and distinguishes this species from Lepas anatifera.