IME, the problem with an anemone getting shredded is the cloudiness and the ensuing decay spiking pollutants (ammonia, nitrite, and nitrate) in the system. If one does get caught in a power head, turn the powerhead off. If possible, remove the guard or inlet from the powerhead and set the anemone down in the tank with the guard. If you catch them early enough, they can extract themselves. I advise against trying to pull the anemone out, as you will often tear them. My LTA let go of the substrate and ended up in an MJ600 once. I was able to follow the instructions above and he's AOK now. I've been fortunate since the one incident with both my LTA and a hadoni.