What in the world is this thing?

[gabrieltackitt]

I found this free floating in my tank this evening being blown around in the flow.

It moves on its own, and is fairly sensitive to light. I’ve attached a few photos and a video as I haven’t even a hint of a guess at to what it is.

 

[Rtaylor]

I can’t view the video, but my first guess would be some sort of nudibranch (sea slug). They usually have very specific diets, did you recently add any coral or macros?

 

[gabrieltackitt]

I can’t view the video, but my first guess would be some sort of nudibranch (sea slug). They usually have very specific diets, did you recently add any coral or macros?

Nothing has been added, other than a few fish, for over a year.

I did recently replace the sand in a tank move with new arag alive sand. But other than that no new rocks or corals.

 

[Rtaylor]

Nothing has been added, other than a few fish, for over a year.

I did recently replace the sand in a tank move with new arag alive sand. But other than that no new rocks or corals.

Does it move like a sea slug (slide across a surface)? Can you see any antenna looking like things? Do you see a head?

It looks a bit like a spotted sea hare?

 

[gabrieltackitt]

Here is a link to the video.

 

[Rtaylor]

Or

Elysia crispata- lettuce sea slug?​

 

[gabrieltackitt]

Or

Elysia crispata- lettuce sea slug?​

Maybe? It doesn’t appear to have any distinctive head or mouth or anything of that sort though

 

[Rtaylor]

@ISpeakForTheSeas ?

 

[DJF]

Whatever it is it is cool! Following to find out

 

[Rtaylor]

Looking at the video, maybe some type of colonial tunicates?

 

[hexcolor reef]

 

[ISpeakForTheSeas]

Or

Elysia crispata- lettuce sea slug?​

Honestly, this would be my guess as well at this point, though I agree that I can't seem to find the head/rhinophores. It's possible that this is just the body of a specimen without the head (Elysia spp. can autotomize their whole body and regrow it from just the head), but I'm not sure how much movement would be seen in the headless body.