What happened to my BGM chalice?

[EmbraceStardumb]

So I woke up today and all of a sudden it has these grayish lines linking between the eyes. Anyone have an idea what happened?

 

[EmbraceStardumb]

Anyone?

 

[greech]

Looks like something stung it with sweeper tentacles or it was munched on. What corals are near by?

 

[EmbraceStardumb]

Nothing near by could sting it. It has good polyp extension when the lights are turned off and there's no coral skeleton showing.