Who is this fertilizing my tank?

[alcimedes]

When I went to feed the tank today, I saw two tubes come out of the live rock I've never seen before.

They appear hollow and mostly translucent.

The larger was at least 2" long, and the one I took a video of. There was another, smaller that was also seeding the water.

They were pumping the water full of sperm/eggs, not sure which. Just wondering what might broadcast spawn like that. I've seen the snails doing similar, but not these tube things.

My descriptions to Google yielded nothing.

I'll include a link to a video in about 20 min. have to wait for it to upload and convert first.

 

[Homestead_Dad]

Looks like a sponge


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[alcimedes]

Do sponges move quickly? I thought they were very slow growing organisms. Whatever this tube it, it retracted quickly when I moved a rock nearby.

 

[CrayolaViolence]

I had a snail doing this the other day in my tank.

 

[alcimedes]

I've had my snails do this before, and it looked very similar. I've never seen just a tube protruding from a hole in the live rock doing it though. I have no idea what was on the other end of this tube.

I don't think it was a snail.