All marine aquariums are populated by polychaete worms.
Most of them live hidden and often only come out at night or when you feed your fish and corals.
If corals or anthozoans show bite marks, they may have been attacked by polychaetes.
In this case, you should act quickly and use a flashlight to examine the aquarium at night.
If you immediately discover some of these troublesome little worms, it's best to remove them from the aquarium before they can cause further damage.
It's generally not helpful to try to catch the worms with tweezers, as they are often cut in half – and each half can develop into a new worm.
Furthermore, you should absolutely avoid handling polychaete worms with your bare hands, as their tiny bristles can cause skin irritation that may last for several days.
The simplest and most effective way to capture these worms is to use a polychaete trap.