Hydrous or feather duster

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Hi all
Still trying to learn about saltwater but I noticed these on some live rock if you shine a light on them they retract just wondering if they feather dusters or hydroids

Thanks

 

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[ISpeakForTheSeas]

Definitely not hydroids- the first pic is definitely a feather duster worm (harmless filter feeders), so if all the tubes in the other pics are sending out similar crowns, they’d be feather dusters too.

 

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Perfect thanks I'll leave them alone