Hammer coral skeleton is showing cracks / inside.

[taegondy]

Hey y'all, it's my first time posting here. My 120 gal reef tank has been doing really well and is about half a year old, and I have this hammer coral i got from my friend at the start of my journey. It's split 5 new heads since I got it and has been doing well. Today when feeding, I noticed the base stalk/ skeleton is kinda cracked open and showing inside. Any idea what could be going on?

Parameters are all within normal range. Calcium was a little higher around 500 last I tested

 

[mcarroll]

I'm not sure yet what you're seeing, but can you post some general info about your tank, how it's cleaned and filtered, as well as any water test results you have, including nutrient levels, s.g. and temperature?