To the naked eye black thread like worms?

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Does anybody have an idea what these thin thread like worms are? They only come out at night.

 

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Here’s a few more photos.

 

[ISpeakForTheSeas]

Not quite sure. I've seen some similar posts where people identified these as either juvenile tubeworms (the OP of this one claimed to have seen them make/making their tubes) or ribbon worms (phylum Nemertea - the OP on this one mentioned dropping a chunk of meaty food into the tank and watching the worms come out when they did, presumably at a different time than normal). Either way, by all accounts, they seem to be harmless, either as filter feeders or as members of the CUC.

 

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Yeah, I was thinking detritus worms. My tank finishing off cycling. It’s just getting past the hair algae and diatom bloom. I forgot that my last reef tank back 15 yrs ago went through a similar process.

 

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I didn’t post the photo but while looking through the microscope I was even able to see one snacking on some detritus on the slide.