I am unsure as to what these are


Reefing newb
Hello All,

I recently purchased this new frag for a small 25g setup. I would like some info on the circled hitch hikers that came with the frag.

1. The one circled in red seems to me like it is some form of a mushroom. It will fill up with water about every 2mins and give one large contraction ejecting the water that it took in (I thought that it was coralline on the rock until I saw it move).

2. The one circled in blue was about twice the size of now, and has shrunk. Not sure of what it is.

3. The one in green was a much darker brown color, then it became very pale brown, and is slowly regaining color.

4. The one in yellow baffles me. It looks like some form of clam, but it has feather-like tubes that stick out of it. The tubes are pink-red in color.

I took these pictures at night with the flash on. Let me know if I should try to get better pictures.

Thanks in advance for any help.

Thanks Aquarian!

Below are some better pics. The tank is 10 weeks old. I bought the rock about 4 weeks ago.






This last photo is from the top. I hoped that it would have come out better (I had to stop the pumps in order to take it).

Btw... Are those creatures good/bad?

Thanks again!


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All the ones I named are good. In the red I also see a limpet (good) and next to the orange sponge on the far right there is green bubble algae (bad) a emerald crab will eat it you can remove it by hand too just don't pop the bubble in your tank when you do a water change take the rock out remove the algae then rinse the rock ( if the bubble popped) in your bucket of waste water. That's a nice rock where did you get from?
In your second to last pic just to the right of the two sticks there is a snail. That snail may (MAY) be a Whelk which are predatory on other snails keep an eye on it.
Thanks for the replies. I saw the bubble algae a few days ago. I will try to remove them (there are 2 of them) on the next water change. There are also 2 of the small darker snails, and 3 hairy-legged crabs of a red color that came as hitchikers, plus a ton of pods and worms. I got this frag from an LFS here in Orlando. It is the only thing in the tank right now (along with the critters). It looked very colorful, and now I know why! Hopefully within a few weeks I will add a couple of fish and CUC. I only have a 25w Coralife light fixure on the tank now with 1x 10,000K and 1x 6500k T5 bulbs. Would that be enough? If I should post these questions on a different thread let me know.

Thanks again!
Regarding the sea cucumber... I thought that they were sand sifters and moved about in the tank. This one is affixed to the rock and does not move from that spot at all. Are there different types of sea cucumbers, including ones that do not move?
They do move around but they will stay in one area when there's food there, but I may be wrong about the cucumber. Does the whole area circled in red fill with water then deflate?