what are these in my tank?

[fenlie123]

found this , looks like coral. dont exsit before, i left county for 1 month, i found them appear when i got back.
my fishes are not healthy and dyng now.

please help

[JetJumper]

Have you done water tests?  If so please post the results so we can help with the fish. 

[fenlie123]

Have you done water tests?  If so please post the results so we can help with the fish. 

I i assume the water condition is bad, since i left home for a while and there was not water change for more than one month.
i did a 1/4 water change this morning.

but i will do a water test later. 

just have not idea about what those are. i picked one up, and it is not hard, so clearly it is not rock or sand.

i have 2 peacock up side down in the tank now. 

[fischkopp]

I almost looks like uneaten food, or maybe detritus. Could it be that something has fallen into the tank?

No matter what it is, I would do a largish 50-75% water change to make sure the water is good. Keep a sample on hte side if you plan to test it later.

[fishycanuck]

Wow, with no water change for a month, many things could be happening, all of them bad. How are the fish now? If you still need help, please post water parameters.