Cocoon sand worms?

[karimwassef]

I've always had a healthy sand bed & while moving, I made an interesting discovery...

<a href="http://s1062.photobucket.com/user/karimwassef/media/F643E770-555F-4868-B658-796DD0AB51E9_zpsctmh5zib.jpg.html" target="_blank"><img src="http://i1062.photobucket.com/albums/t496/karimwassef/F643E770-555F-4868-B658-796DD0AB51E9_zpsctmh5zib.jpg" border="0" alt=" photo F643E770-555F-4868-B658-796DD0AB51E9_zpsctmh5zib.jpg"></a>

<a href="http://s1062.photobucket.com/user/karimwassef/media/D462E040-6F57-4168-BB6D-79A17D8DDD96_zpstmgnomjv.jpg.html" target="_blank"><img src="http://i1062.photobucket.com/albums/t496/karimwassef/D462E040-6F57-4168-BB6D-79A17D8DDD96_zpstmgnomjv.jpg" border="0" alt=" photo D462E040-6F57-4168-BB6D-79A17D8DDD96_zpstmgnomjv.jpg"></a>

<a href="http://s1062.photobucket.com/user/karimwassef/media/7962413E-29FD-4115-904E-B786F243889B_zpssnpkh7mx.jpg.html" target="_blank"><img src="http://i1062.photobucket.com/albums/t496/karimwassef/7962413E-29FD-4115-904E-B786F243889B_zpssnpkh7mx.jpg" border="0" alt=" photo 7962413E-29FD-4115-904E-B786F243889B_zpssnpkh7mx.jpg"></a>

First, no stink.. no sulfur smell in almost all of the 32" x 96" x 3" volume- the exception was where I had allowed rock to settle into the sand. Almost every rock was suspended though- so the sand stayed very soft and clean.

<a href="http://s1062.photobucket.com/user/karimwassef/media/B2E4021E-B858-45C7-B258-3FC772080C0A_zps4vxl8y1g.jpg.html" target="_blank"><img src="http://i1062.photobucket.com/albums/t496/karimwassef/B2E4021E-B858-45C7-B258-3FC772080C0A_zps4vxl8y1g.jpg" border="0" alt=" photo B2E4021E-B858-45C7-B258-3FC772080C0A_zps4vxl8y1g.jpg"></a>

Second, the worms... I was expecting the normal worms

<a href="http://s1062.photobucket.com/user/karimwassef/media/18458166-DC21-4C43-8F52-5D072DA13424_zps25ckh3u5.jpg.html" target="_blank"><img src="http://i1062.photobucket.com/albums/t496/karimwassef/18458166-DC21-4C43-8F52-5D072DA13424_zps25ckh3u5.jpg" border="0" alt=" photo 18458166-DC21-4C43-8F52-5D072DA13424_zps25ckh3u5.jpg"></a>

But I also discovered these very strange sand cocoon worms. This isn't sugar clumping of sand. This is a worm inside a very fragile spherical sand cocoon... anyone know what this is?

<a href="http://s1062.photobucket.com/user/karimwassef/media/D0F82F5A-AA0D-4A83-9A5B-16FA092D3C7B_zpsiogfv181.jpg.html" target="_blank"><img src="http://i1062.photobucket.com/albums/t496/karimwassef/D0F82F5A-AA0D-4A83-9A5B-16FA092D3C7B_zpsiogfv181.jpg" border="0" alt=" photo D0F82F5A-AA0D-4A83-9A5B-16FA092D3C7B_zpsiogfv181.jpg"></a>

<a href="http://s1062.photobucket.com/user/karimwassef/media/6E9D72A7-1A4C-44CD-9111-7A5C71DC4E08_zps9d3upafo.jpg.html" target="_blank"><img src="http://i1062.photobucket.com/albums/t496/karimwassef/6E9D72A7-1A4C-44CD-9111-7A5C71DC4E08_zps9d3upafo.jpg" border="0" alt=" photo 6E9D72A7-1A4C-44CD-9111-7A5C71DC4E08_zps9d3upafo.jpg"></a>

Thanks

 

[Subsea]

Neat. Can you see them move?

http://rockymountainwormcompany.com/cocoons/

I thought that this link was somewhat analogous to your situation. Instead of free swimming larvae from worm spawn, this looks like eggs. As long as it is not alien babies.

 

[karimwassef]

No. They were completely inert when I pulled them from the sand. they were generally about an inch deep and the sand balls were about a 1/2" - 3/4" in diameter...

I found them all over the sand bed except the black anaerobic areas.

Sometimes they group together like cells but usually they were separate. There were probably a few hundred...

Once I added them to the new tank again, they disappeared overnight into the sand again.

I think they use long sweepers to grab food from the sand but don't actually move.

 

[WVfishguy]

These may be vermetid snails. They are motile as young, sessile when adults. They use slime nets to catch food. I've had vermetids with long white sweepers.

My employee, who was a reefer, identified them for me. I don't like them because they produce a sharp, calcareous cocoon which causes cuts and scrapes when you work on the tank. I've never seen any damage from them, and I've had them for decades.

There are 'net articles which indicated they prevent algae grazing by fish, and I can believe it.

I could be totally wrong about these critters - they may simply be another type of annelid.

I just transferred my live rock out of my 75 gal. quarantine tank to a 90 display. The now-exposed deep sand bed in the 75 has a lot of these critters in it.

 

[karimwassef]

Do yours form round sand cocoons? Got pics?

These look to be adult forms - they're sessile. I don't think vermetid live in sand and these guys have a relatively fragile cocoon and tube. Nowhere near the hardness or sharpness.

 

[WVfishguy]

Do yours form round sand cocoons? Got pics?

These look to be adult forms - they're sessile. I don't think vermetid live in sand and these guys have a relatively fragile cocoon and tube. Nowhere near the hardness or sharpness.

The more I think about, the less I'm inclined to believe the "cocoon critters" are vermetids. I simply thought they may be a vermetid I'm unfamiliar with, but I now believe all vermetids develop a hard tube.

I believe these are an annelid. They remind me of Caddisfly larvae.

My critters look like yours. I've seen those cocoons many times over the years. I've never thought twice about them, they are just a few of the oodles of critters in the refugium sand bed.

I don't worry about bugs in the 'fuge. (I'm not saying the OP is worried).

I'd like to ID everything I've ever seen, I'm a biology buff, it's how we are. But I believe the more the merrier, as long as livestock isn't harmed.

Some marine biologist need to chime in here. I'd also like to know what these critters are.

 

[karimwassef]

I haven't seen them before. I like to understand the role of all my pets and confirm they're not pests.