Yes it will kill the beneficial bacteria , but the other rock you have will reseed the rock in time. This is not the only rock you have is it? Believe me you don't want this stuff in your tank and don't try to remove it in your tank it will release spores and grow everywhere...there are products to remove apstasia but for myself in the past I took no chances I boiled a rock when i had apstasia...do a google search and get info...on this site then decide what to do....Ya that looks just like it....will boiling it kill all the beneficial bacteria?