Help! Did I kill my Toadstool?

[TheReefGeek]

Poking it like that would not kill it. But something is wrong in your tank for this toadstool to become like this. Have you tested all your water parameters, including salinity and temperature? How is everything else in the tank doing?

Depending on how far gone it is, you might want to frag off any good pieces so they might re-grow healthy.