Pineapple (scypha) sponge?

[chiqui bb]

I've recently seen a few of these in my tank. Some are attached to the rocks, some are attached to plants. And they move around! I find them in different spots.

What I'm curious about is how they feed. I've been watching one of them with my magnifying glass and it seems that it has a long string that comes out of the top and waves around in the current. If I watch closely, it appears to suck the string back in and extend it out again but it takes such a long time for this to occur and I'm really squinting to see it. Looks like a single string from a spider web. Anyone else seen this before or is it just something floating in the water column?

 

[reeffreak]

What you are describing is not a sponge.

Sounds more like a vermetid snail.They are a snail that lives in a tube.They throw out a sticky fishing line,catches food and reels it back in.Call the couch potato of snails.Reef safe but sometimes reef annoying.Ths strands of cobweb can keep some small corals from fully opening.

 

[chiqui bb]

Thanks reeffreak. You're right. I do have some pineapple sponges but they are a little larger and look fuzzy. The little "fisherman" is smaller and not fuzzy. I just assumed they were the same creature!