Hard, dark crusty stuff on hammer stem

[hanabata]

Hey all,
I have a hammer that’s not opening, and it has a dark, jagged, stuff, and crusted on its stem. I’ve read threads about algae, but I assume the algae would be soft, but maybe not. I’m pretty new at this. This stuff is hard like tree bark.

I have another hammer in the tank that’s fine. Its stem is smooth.

Wondering if I should try hydrogen peroxide in case it is some kind of algae and try to scrub off just the stem.

I’ve attached a picture of the affected coral, my other hammer that seems to be doing fine. And lastly a cyphastria. Is this thing dead? I don’t see any polyps, but it still has color on the base. It used to have small, yellow polyps.

Thanks for reading:)

 

[Macbalacano]

For Hammer, those look like vermatid snails. You can scrape them off, or glue them shut.

 

[EeyoreIsMySpiritAnimal]

Vermetid snails.
They may or may not be irritating the coral.
Remove the frag from the tank and scrape/chisel the entire shells off and rinse in another container of tank water before returning the coral to the tank.

 

[EeyoreIsMySpiritAnimal]

And, yes. The last coral appears to be dead. (Vermetids would not have killed it...)

 

[hanabata]

Thanks all! I love this site. You all are so helpful:)