Can anyone ID this

[Justin Thain]

Can anyone ID what these white spots are called? I'm assuming they are harmless, and most likely some type of duster incased in a calcium shell. First picture is an overview of the back of the tank, while the next picture is as close up to the back as I could tank

The next pictures are ones that looks similar that are on my candy cane, but are larger in size.

 

[ReeferMaddness843]

They look like spirorbid worms. Come and go over time. Filter feeders

 

[Tahoe61]

^ Yup.

 

[Jisko]

watch out though... they can really take over powerheads and begin to encrust in your overflow box.... I had a powerhead that got covered with them