ID help.

[hondas3000]

it will look green under blue light. It will grow like weed unlike other kind of zoa .

[gregzz4]

Look like palys to me too. If they stay brown get rid of them - unless you like brown . They'll overgrow your rock. I had similar ones and they're a pest.
Above your featherduster I see a vermetid snail - it'll have a hard tube. Mash the crap out of it before it spreads. You've gotta dig into the rock a bit to kill it.

[gobytron]

Never had a problem with vermited snails...

Why kill them?

You don't like the web?

Also, thats probably a Hydrozoan...maybe not a vermited.

[Aquattro]

Originally Posted by gobytron

Never had a problem with vermited snails...

Agreed. I find them interesting. I guess I've never had a huge amount, but the ones I had were fine for years.

[Snappy]

If their web gets on corals it can irritate them if it stays there for extended periods of time.

[gobytron]

Your tank would be pretty bare if you got rid of everything that MIGHT irritate a coral.

I've also never heard of vermited snails becoming an issue as far as spreading goes....if they are, it is probably an indicator of something seriously off with your chemistry.

They are calcareous and take some time to grow.

They are also a filter feeder and help to remove debris from your water column.

I would love to see some documentation of one ever causing any long term damage to any coral...as i have only ever read about it third hand.