Mystery Stuff growing in tank!

[acura rsx star]

Okay, so after having my tank for a year and a half. After two total wipeouts I think I finally managed to maintain a good ecosystem! All corals are growing (and reproducing) and all fish are healthy! There's also a few things that were not in the tank before that have shown up.. Maybe you guys can help me figure them out..
Here's a full shot of my tank...

1. this guy showed up on a rock....(pretty much in the center of the tank) I'm not sure if it's a coral or an anemonae. If something gets near him he'll retract really quick. Any ideas?

These last two things are in a corner of my tank hidden by the rocks, where there is very little light. I'm wondering if they damage the tank in some way and if they need to be taken out??
3. A section of a mesh-like stringy white stuff...about the size of a quarter...
4. These guys worry me a little bit. They have tube-like bodies and small white spikes. I have NO CLUE what they are. They are only a few millimeters long and again, are in the dark.

 

[shrimpi]

#1 is aiptasia: a pest anemone. It will multiply and sting corals.... and its ugly. Get some joes juice or boiling water and inject that sucker!
#2 is a gorgonian.The polyps that are coming out are a way for it to filter feed... kind of like a featherduster. Keep it in good flow and not very bright light and should do well. Its a coral basically. Not sure if it has its own 'class' but its basically a 'coral'
#3 is a sponge. Filters the water and is a sign of a healthy tank/environment. I have a big one that looks like SNOT. But, whatever. Just leave it be.
#4 I have those behind my overflow and I have no clue what they are. I assume some sort of sea squirt ? Pretty sure they are harmless but maybe someone can chime in
Jessica/Shrimpi

 

[kidreef]

crap i just scrubed some white stringy stuff off my rocks cause i didnt know if it would harm my tank

 

[shrimpi]

no problem.
Its not very pretty so who cares.

I think Ill accidentally scrub some of mine off this weekend. lol
Jessica

 

[acura rsx star]

Originally Posted by Shrimpi
#1 is aiptasia: a pest anemone. It will multiply and sting corals.... and its ugly. Get some joes juice or boiling water and inject that sucker!
#2 is a gorgonian.The polyps that are coming out are a way for it to filter feed... kind of like a featherduster. Keep it in good flow and not very bright light and should do well. Its a coral basically. Not sure if it has its own 'class' but its basically a 'coral'
#3 is a sponge. Filters the water and is a sign of a healthy tank/environment. I have a big one that looks like SNOT. But, whatever. Just leave it be.
#4 I have those behind my overflow and I have no clue what they are. I assume some sort of sea squirt ? Pretty sure they are harmless but maybe someone can chime in
Jessica/Shrimpi

Thank you soo much!

 

[renogaw]

number four are qtip sponges, beneficial

 

[acura rsx star]

Thank you so much guys! I actually did some research and found that the peppermint shrmp actually eats Aiptasia, so I'm going out to buy one tomorrow! Hopefully that annoying anemone will be eaten up soon! Thank you so much for the quick replies!

 

[renogaw]

Originally Posted by AcUrA rSx StAr
Thank you so much guys! I actually did some research and found that the peppermint shrmp actually eats Aiptasia, so I'm going out to buy one tomorrow! Hopefully that annoying anemone will be eaten up soon! Thank you so much for the quick replies!

SOME peppermints will eat it. depends on if they are tank raised or not. there's tricks to getting them to eat if they don't automatically

 

[zman1]

#3 Leather Lattice Sponge - Clathrina sp.

 

[puffer32]

I don't think a peppermint will eat that aptashia, its huge. I would go with joes juice on that monster.