no its not a spaghetti worm, the lines are very very thin, almost unseen without a good eye and flashlight. it retracts to bring in particles floating in the water
If it retracts and brings particles in from the water I dont think it is anthing that is happening becuase of the zoa's. It is probably a tube worm or a vermetid snail that is living underneath the zoas or in a crack of the rock. Do you feed your food with selcom?
what is selcom?
It's actually Selcon, though I've never heard of it being used to feel coral. Most often people soak food in it to help get finicky or sick fish to eat.
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