possibly a what is this stumper
 

Long story short I have a tank that I check on once a week at my old house that is sitting around waiting for spring so that I can transport all the livestock to my new house. Today I stopped over to feed the fish and check on everything and I noticed some fish were missing. I figured I would get out my flashlight to see if I could see them behind the rocks. I did not find them, but I did find this guy. I cant say I have ever seen anything like it that I can think of. I don't recall every seeing anything there before either.

Any ideas on this one? Sorry for the crappy video I was trying to get my phone to focus and make it move with the flash light at the same time.

<iframe width="560" height="315" src="https://www.youtube.com/embed/PzeAf6BELdM" frameborder="0" gesture="media" allow="encrypted-media" allowfullscreen></iframe>

I don't know for sure, but I'll be surprised if it's not a nudibranch of some sort.

rough size of it is the size of a baseball for the part you can see

looks like a scallop.... looking at one end, it's 'open' and feeding. if you tap the glass, does it close?

Like watching a bigfoot video.

it didn't seem to care if I tap the glass. That is what it looks like though doesn't it? My first reaction was holy crap i have a huge clam back there! I didn't see a shell though. Now I am even more antsy about moving the tank so I can see what it is.

I also thought nudibranch. I can't see it well - does it have a shell on it's back? It's not a cone shell is it? That would explain the missing fish. I'd be careful handling it, whatever it is. No way I'd touch it.

This is a LOT like watching a bigfoot video! Fish nerd sasquatch!

Can we get an update?

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Write into WWM and ask specifically for Lynn Z.

Is it possible that it is a cuttlefish and somehow hitchhiked into you tank? Sounds stupid...I know.https://uploads.tapatalk-cdn.com/201...5b1e3373b7.jpg

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Lynn isn't going to be able to identify it by that video.

Havent figured it out yet. When I move the tank and pull out the rock I will find out. For now its just a waiting game. Its behind the very bottom support rock in the back :(

Yes, I'll be interested to see what it looks like when you get it out. It has characteristics of several things. I don't think it's a nudibranch, and I see a mantle that would make me think those tentacles are not from a cuttlefish. And it's definitely not a snail.

I don't know about nudibranch. If it is one it would have to be huge. The part we can see in the video is at least 6" unless there are some that get that big?

Ok I messed with it a little more today when I stopped over to check everything out. I got it to close up. It appears to be some sort of clam/oyster type thing. When it closed up it looked like it was black and had a really spikey shell.

This thing is awesome! Stuff like this is why I love this hobby. There at the end where it moves - yikes! Please do keep us updated! Can you get any more images?

Here is one of it closed.

http://i446.photobucket.com/albums/q...psb2hiz1gp.jpg

Would you please just go in and get it? This is driving me crazy! :uhoh3: :uhoh3: :uhoh3:

(Or just crazier - I've always been a bit nuts!)

This thing is a treasure! You are lucky! It's so big - did it grow that big in your tank? Must be happy!!

What is it though?

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ya i haven't added anything to my tank for years...... nor have I done a water change in probably 2 years. The softies hate it when I do a water change so I just left it and I am getting great growth. Weird stuff just kind of shows up lol. It's killing me to not know what it is as well. I'm sure its just some common oyster or clam or something. It would be cool if its something rare though :)

I had a roughly 8" abalone show up one day as well about 2 years ago from behind the rockwork. He ended up dying and I have a pretty good size shell off of him.

I would go in after it, but I have like a 2 foot toadstool that I don't want to make angry. He's kind of my prized possession honestly as dumb as that sounds. But he sits right on top of it and I don't really have a place to put him while I move everything around to get to it.

I have a snail as well that is about the size of my fist that I've had for I bet 10 years at least lol. He actually has the power to eat the coraline off the glass haha!

I envy the OP.

IMO, one of the best things about marine aquaria is finding critters you did not know you had (unless they destroy your other critters).

My setups are so old that only pods and worms live in them. That is the safe way, but boring as hell.

I enjoyed my tanks more when I had a plethora of weird inverts swimming/crawling in the refugiums. :(

I googled around for a hairy brown pteriomorphia and found three websites from nature enthusiasts with photos that look very similar to this spiny brown fellow. Unfortunately they did not identify the species. I also saw it in a Nat Geo video, but they did not identify the species either! It is hard to safely do an image search for this thing.

I'm not sure if it is a clam or cockle or something else. I imagine this is pretty rare to be that big and happy in the aquarium. Do you know where the live rock came form (i.e. Florida, indo-pac, etc.)?

foster and smith's probably 10 years ago or better. Not sure where it came from. It came in one of those 50 lb. boxes of live rock that they sold at if I remember right the first frag swap they had back in ..... 05 or 06? I want to say Fiji premium or something to that effect if I remember right though.

The rock has been in 3 different tanks since I bought it. It is about to be a 4th tank.

The closest thing I can just straight up guess it is would be a thorny oyster maybe with a super huge mantle. It seems like the mantle is like 3 times the size of what I can see of the shell or more.

Mantle gets me too! It's huge in the video/pic. Whatever it is, I'd say you are extremely lucky and it is a very cool thing.