What is this on my rocks?

[keithw283]

Hey everyone. These white things are on most of my dry rock and was wondering what they are. My tank tear down wasn't very graceful. I got all the fish and little bit of coral I had out and then just turned everything off so I could finish another day. Another day ended up being about 6 months later so I had all this stagnant water and for about a month I had the lights still on even though nothing was left in the tank. I'm trying to clean these rocks so I can use them again but these things will not come off. I used a pressure washer on the rocks and have been scraping with a toothbrush with very little progress. I set up a rubbermaid container today to cure them. Will that help and will putting these rocks in the tank cause issues if I can't get them off. Thanks in advance.

 

[justmee]

I'm not too sure what they're called but I have heard people calling them barnacles, but they're not harmful and I have some in my tank...

 

[VB313]

Tube worms harmless filter feeders probably deceased though

 

[KJ]

Death Feather duster.

 

[tankstudy]

Small species of feather dusters.