My very first SW tank

[Chipie]

Hi thanks for the input. The Yellow tail Damsel and the Clown seem to be getting along. I'm getting a little bit of hair algea on the front glass but not much. Also i'm getting Coraline algea on the back, the glass and on some seashells i have in there for the hermits. Is getting coraline a good or bad sign?

I've got a lot of little things crawling the LR at night. Like tiny grayish shrimps. Don't know what they are.
Also found a few snails that only come out at night. They are small also.

And there's something either in the sand or in the LR that extend some kind of tentacles. (long, bright red and thinner that a hair)
Any idea what it is. Unfortunatly i don't have a good macro lense needed to photograph tiny things.

Oh i almost forgot, there's some tubes coming out of the rock with the zoos that have something coming out of it. Look like a little head with two antennas. What could this be.

I'm sure they are all common things but being a total noob. I have no idea.
Thanks