Can you help me ID these random things on the rock??

[thatg33kgirl]

Hey all, I was wondering if anyone could help me ID some of these things on my rock- also if you see anything else on there that I should keep my eye on let me know!! Thanks in advance!

a. Some kind of tube...worm? It doesn't have feathers, and if you move around it, it will disapear into the tube and reappear later. Does it have a name or is it a pest?
b. Strange white tentacles. They seem to reach a few inches at max, sway in the currents, and when startled disappear. Is this thing a pest and should I get rid of it? Or is it just a random... pile of tentacles??

Does anyone know what kind of corals these are? Sorry for the quality of the pic, I just had finished stirring up sand so they aren't as clear as they should be. They are white with light green tentacles.
Thanks!!

 

[thatg33kgirl]

Another one- itty bitty sea urchins??? Are they good/bad/extremely cute?! I vote cute

I just noticed them coming out tonight, and they do move ever so slowly. Are they pests and if not, how should I care for them?? Thanks!

 

[katsafados]

a - most likely a mini feather duster.. I have the same orange/red ones with white tubes (not harmfull)
b - spaghetti worm (not harmful)
corals - might be a rock anenomie
last one looks like sea urchins to me..

 

[thatg33kgirl]

Thanks Katsafados- we were noticing last night the worm (a) does put out reaaalllyy tiny feelers late at night. Yay they aren't harmful, its kinda cute! Also good about the worm and corals, if anyone else has an ID on what kind of corals and if they need to be spot-fed let me know.
Also if anyone knows anything about the urchins, let me know. Are they baby ones, or is that their full size? And how should I feed em? Thanks all!!

 

[speg]

Can't really tell what's in the first pic. Can you get a more up-close shot?
The second pic looks like hidden cup coral.
The third looks like little urchins...they'll get bigger...they're only a pest if you don't appreciate what they do. One of the things they can do is scrape at the coralline algae.

 

[thatg33kgirl]

Hey Speg, even with my Nikon which is used to taking very detailed pics of art and jewelry, it absolutely refuses to take better pics of my tank!! Perhaps its because it is bowed-front? I'm not sure. But I'll try to get some better pictures of them later today.
Cup corals, ok, good I've been spot feeding them. Yay I did something right!
I love my tiny little urchins. Here's what I'm hoping for-- awww, look! They've gotten too big for the tiny tank! Time to get a bigger one!!! (Its been a pain trying to convince the family to get/spend electricity on yet another tank!)