White stuff on hermit crab shell

[pbandjealous]

Absolute newbie to salt water tanks. Tank is only about a month old, recently added a handful of snails and blue leg hermits. Noticed one crab has some weird white stuff on his shell. Can anybody tell me what this is?

 

[sunken3]

tube worms...

 

[pbandjealous]

Harmless or should I be concerned and remove him?

 

[moz71]

Harmless no worries

 

[ZipAdeeZoa]

IME tubes of that colour and shape typically belong to harmless featherdusters