Please help to identify this worm

[Yoonsuk Choi]

I never have seen this kind in my 8 years of reefing.
there are two of them in the video.

long dark body and two short tentacles at the end.
It only comes out at night, and hides as soon as light on.

I think they are hitchhikers from the live rock, because my tank is only 2 months old, and all I put is fish and cleaning crew inverterbrates.
The live rock is delivered fresh from Taiwanese ocean(I'm in Seoul, Korea).

My Taiwanese reefer friend said he has many of them in his tank, and he thinks it does not harm corals and fish, but does not know exactly what it is.

Anyone know this creature?

 

[Gumbies R Us]

Do you have photos of the worm? Videos can be weird and not load on iOS devices

 

[vetteguy53081]

Possible Eunice worm

 

[Yoonsuk Choi]

Possible Eunice worm

It does not have exoskeleton so I don’t think it’s arthropods thank you

 

[Yoonsuk Choi]

Do you have photos of the worm? Videos can be weird and not load on iOS devices

 

[ISpeakForTheSeas]

That's a female Bonelliid Spoon Worm/Echiuran - most spoon worms are harmless detritivores (good CUC), but a few (likely including yours) have a toxin (Bonellin) on their proboscis (the forked "mouth" mentioned above) and/or skin; these eat things like small pods that succumb to the toxin when crawling on/over the proboscis.

These would probably be fine to keep in the tank as long as you think your critters are smart enough not to touch the proboscis, but it may carry some risk (especially for smaller critters, and especially if your female has one or more males - which are tiny - living with it so that it could reproduce):

be aware that it is toxic (the toxin is called Bonellin, and I’m not sure about it’s effects on people), and please handle it with care and a good pair of gloves.

If you decide to keep it, I'd probably suggest running carbon and doing regular water changes to be safe.

Bonelliid spoon worms exhibit extreme sexual dimorphism - the females are large while the males are extremely tiny and often/always live literally inside the female. So, by seeing the worm's regular-sized proboscis extended, you can tell it's female (no idea if it has a male with it or not though).

Unfortunately no idea how harmful the toxin is - as a general rule, the physically greener the worm, the more toxic I would expect it to be, but I don't know how much of the toxin it would take to harm a small fish.

 

[Yoonsuk Choi]

That's a female Bonelliid Spoon Worm/Echiuran - most spoon worms are harmless detritivores (good CUC), but a few (likely including yours) have a toxin (Bonellin) on their proboscis (the forked "mouth" mentioned above) and/or skin; these eat things like small pods that succumb to the toxin when crawling on/over the proboscis.

These would probably be fine to keep in the tank as long as you think your critters are smart enough not to touch the proboscis, but it may carry some risk (especially for smaller critters, and especially if your female has one or more males - which are tiny - living with it so that it could reproduce):

be aware that it is toxic (the toxin is called Bonellin, and I’m not sure about it’s effects on people), and please handle it with care and a good pair of gloves.

If you decide to keep it, I'd probably suggest running carbon and doing regular water changes to be safe.

Bonelliid spoon worms exhibit extreme sexual dimorphism - the females are large while the males are extremely tiny and often/always live literally inside the female. So, by seeing the worm's regular-sized proboscis extended, you can tell it's female (no idea if it has a male with it or not though).

Unfortunately no idea how harmful the toxin is - as a general rule, the physically greener the worm, the more toxic I would expect it to be, but I don't know how much of the toxin it would take to harm a small fish.

It must be Bonellia Viridis… I checked again and it looks green. And few days ago my skimmer poured greenish color water, but not sure it’s from that worm. I need to get rid of it, but no idea how to do it.. maybe I need to pick up the whole rock and dip it? Will coral rx work?