Let me introduce you to an old friend of mine, the Fulgida worm, Pretty isn’t it? Contrary to its cute and jelly-worm-like appearance this is NOT something you want in your aquarium.
Fulgida worms are voracious nocturnal predators with a sweet tooth for molluscs. These hell-worms can completely decimate the snails in your clean-up crew and feast like kings on your precious Tridacna clams (Giant clams). Fulgida Worms secrete a toxic slime coat which they use to stun and immobilize their prey, leaving an empty mucus covered shell to be discovered the next morning as the only evidence of their attack. This mucus also serves as a lubricant for the worm, allowing it to retreat with lightning speed back into its burrow when disturbed. It will rarely entirely leave the confines of its burrow and will usually extend to great length beyond it, while still anchoring itself inside with its tail. Fulgida worms also possesses a good pair of very visible eyes and are extremely sensitive to both light and movement. These factors combined makes it not only an extremely undesirable house guest, but also one that is very difficult to evict.
The most simple method to remove them is to go on patrol at night with a “red flashlight” and a pair of forceps. This method requires a fair amount of patience and determination, as when spotted you must move carefully to lower the forceps in position without spooking the worm, before quickly grabbing it and quickly pulling it out. As mentioned, the Fulgida worms slime coat is toxic, so its best to avoid getting any of it on your skin.
A second method is to build a worm trap baited with raw scallop meat from the supermarket. This may or may not work depending largely on how much “live food” it has at its disposal.
A more inconvenient, but by far the easiest method, is to identify the rock where the worm retreats into and simply remove the whole rock from the tank with the worm still inside it.
Armed with this knowledge, you should now hopefully be better prepared to identify, locate, extract and terminate this pest should the day come that you suddenly start finding empty mucus covered shells on the sand.