White On Crab/Snail Shells

[marinebio13]

I just noticed some white spots and lines on the shells of my margarita snails & hermit crabs. I never noticed it before. There also appears to be something coming off the shells that is waving in the current. I don't notice anything on my two clownfish. Does anyone know what this is and should I be worried? Do I have to do anything to treat it?

Thanks!

 

[snulma1]

Looks like a sporbid worm. They are annoying but harmless