Can someone help me ID these?

Well... I was given some species which I don't think I recognise at all
Hopefully someone can ID these, and whether or not they are reef safe, dangerous or beneficial for cleaning. The tank is fish-less/Coral-less/zero ammonia/nitrite (I just checked it again today), so probably nothing will happen yet. Otherwise I need to return these creatures.

Sea cucumber?

Brittle Star?

Not sure what kind of crab... :-X

 

You are indeed correct on images 2 and 3.Image one could be some type of sea hare vs cucumber, very hard to tell from the image.

I am guessing you bought live uncured rock?

Please google polyclad flatworm and see if that looks like it. There is not enough contrast between the rock and the subject to make out details. If it shows up again remove it and place in a container for image.

Crabs are mixed bunch, some horrible some fine. If possible I would remove crab and put him in the sump.

You have some great hitchhikers.

 

The first thing looks like a dead, slimy biomass of some kind. Got any better pictures?

 

If the crab is hairy there is a good chance its a bad crab, if not than it might be beneficial

 

Hi, thanks all, I am going to get a better pic tonight. Day 5 - still no ammonia, nitrite and nitrate, and low phosphate (very low). Salinity at 1.025. The first pic is confirmed black sea cucumber, the second one is brittle star and the last one is still unknown but it's definitely not a hairy crab. I have 2 corals to add later: both soft leather and mushroom corals which I need to ID too. I also have a very small Halimeda.

 

More pics...

Black sea cucumber? Size is about 2.5".



Bad crab? I take it back, this one looks pretty hairy but very small in size. About 1"



Bunch of soft corals. Can you ID them?

 

Ugly little crab!! lol

As for corals I see some zoanthids in the lower left corner which is an easy to keep softie.
The big one is not a softies but actually an lps. Hard to tell still looks very closed up maybe someone else can help there.
On the tall part I see 2 corals, the lower one being a mushroom and the upper one maybe another lps like an acan of some sort.