Ha! Indeed salty. Aiptasia is an invasive anemone that can sting fish and corals. It spreads very easily, and is notorious for being nearly impossible to completely remove from a tank. There are some fish that eat it, but they can be picky. I spent $300 a few years ago on berghia nudibranches, which only eat aiptasia, but one of my fish enjoyed them for a snack. That fish has gone to the big fish tank in the sky, so now I have a new shipment coming today.

Pictured is an expensive powerhead that seized when they started growing on it. Not pictured are dozens and dozens more.