what happened to my coral

[sawyer010]

hello, everyone
what happened to my wilsoni coral? i have kept it two monts and all is good. and i have checked today, and found this. i feed it three times a week
and my water parameters :
ammonia:0
nitrite:0
nitrate:2ppm
PO4:0.018PPM
PH:8.0
CA:440PPM
KH:11.5
the temperature of water is 23°

 

[vsolovyev]

Have you had anything fall on it? Maybe a rock or somthing. Somthing could have been munching on it too, what inverts/fish do you have in the tank?

 

[sawyer010]

Have you had anything fall on it? Maybe a rock or somthing. Somthing could have been munching on it too, what inverts/fish do you have in the tank?

i have two wrasses and some snails in my tank,

 

[Uncle99]

Looks like a test bite to me.