Barnacle larva will attach themselves to, and grow on, any firm suface - rocks and stones, ship and boat hulls, pier pillars, shellfish, crabs and lobsters, and even some seaweeds.
I hate barnacles! As a kid, it was my job to scrape the barnacles off the bottom of my dad�s boat when he pulled it out of the water at the end of each boating season. It was no easy task. And if you are in the water and brush against a barnacle covered object like a piling or such, it is like brushing against a bunch of little razor blades.