Animal inside snail shell / coral / hermit crab / stuff in chaeto

Hey everyone, first post here, ive read a lot on the site, glad i found it. So I have a couple ID questions.

1. I just got a dozen or so empty shells from my LFS. i noticed a bristleworm and this clear, long sticky tentacle coming out of one of the shells. Any idea what the sticky tentacle is? In some pictures there are grains of sand stuck to the tentacle.

2. I picked up some chaeto macro algae from someone on craigslist, he told me the white stuff in the picture were produced by something living in the refugium (I dont have a refugium right now, and my fish are in quarantine, so i just clipped it inside the tank).

3. I bought the frag pictured from another LFS because it had the kenya tree on it. They said the flat part had a dieing piece of SPS. It has been about a month and it looks to be doing OK... but what is it?

4. I bought a couple hermit crabs from the same guy who had the chaeto, and there is this one with brownish, possibly hairy legs. note its eyes are black/grey striped. Is it reef safe? (he had it in an established reef that he is breaking down because he is moving)

Thanks,

Dylan

 

The sticky tentacle is a harmless tubeworm.

The coral on the end is possibly Montipora nodosa

 

I noticed your chaeto also has some Caulerpa algae mixed in. Personally, I would not put it in the display tank unless I had some hungry tangs to eat it. Caulerpa will spread into live rock and be hard to get out.

Jack