Found small worm crawling on coral, not sure if bad or good

[Mortimer452]

Pic below, sorry for the poor quality. Found this guy on my GSP frag today, dark red/purple with white stripes, he's pretty small about the size of a pencil lead, maybe 2mm across and 30mm long. Slithered off into the rocks right after taking this pic.

Flatworm of some type? Should I try and remove it or leave him be?

 

[WalkerLovesTheOcean]

I have this exact worm in my tank, but I have no idea what it is.

Following.

 

[Mortimer452]

At the time I took the pic I actually just thought it was a growth or scar on the coral, didn't even realize what it was until it started moving! The color almost exactly matches the GSP

 

[The_Paradox]

Picture is blurry but from what I can see it looks like a striped peanut worm. That or a starfish… shrug.

 

[Mortimer452]

It looks pretty much just like the first photo here (but smaller probably), but not much information in the link on that specific species. It's definitely a worm not a starfish arm, I saw both ends of it as it slithered off the coral.

 

[vetteguy53081]

Pic below, sorry for the poor quality. Found this guy on my GSP frag today, dark red/purple with white stripes, he's pretty small about the size of a pencil lead, maybe 2mm across and 30mm long. Slithered off into the rocks right after taking this pic.

Flatworm of some type? Should I try and remove it or leave him be?

Body too long to be a peanut but looks like an Autolytinae worm which is a member of the syllidae group and eats uneaten food but can also turn on other clean up crew. Not worth the risk And I would eliminate it or place in sump to feed on detritus

 

[ISpeakForTheSeas]

It looks pretty much just like the first photo here (but smaller probably), but not much information in the link on that specific species. It's definitely a worm not a starfish arm, I saw both ends of it as it slithered off the coral.

I actually think you're right here about this being a ribbon worm - it's not a Syllid worm as it doesn't have the bristles found on polychaetes, and the striping heavier/more consistent than I'd expect from a peanut worm (though some could potentially look like what's visible in the pic).

Probably a ribbon worm (Nemertean) of some kind, but seeing its proboscis everted could confirm that. Ribbon worms are predatory. They hunt using toxins they secrete through their skin and proboscis - don't touch them barehanded:

"Certain nemertean species are known to contain remarkably potent toxins: pyridine alkaloids, tetrodotoxin (TTX), and cytolytic or neurotoxic peptides."*

(For the record, tetrodotoxin is what makes pufferfish lethal when ingested).

Anyway, if it's a big one, you would want to remove it.

*Source:

The Toxins of Nemertean Worms - PMC

Most ribbon worms (phylum: Nemertea) are found in marine environments, where they act as predators and scavengers. They are characterized by an eversible proboscis that is used to hunt for prey and thick mucus covering their skin. Both proboscis and ...

www.ncbi.nlm.nih.gov