Was it him?

[Abijennah]

Found this conch in a bad state, wondering if the most likely culprit is

 

[Timfish]

It wasn't the thin strip hermit. My guess would be damage from when the tank was aquascaped. Those conch shells are pretty thick snd wouldn't be easy to break

 

[Thomas Jedlicka]

I wouldn't imagine many crabs could do that to a conch shell. Probably crushed by rock work