Basicly, Rock is rock...and is not "alive"...
It is the stuff "on" the rock that gives it the term "Live rock"... Bacteria, algae (micro,macro,coraline,nuscience,etc), feather dusters, worms, pods, and assorted micro and macro flora and fauna...etc...etc..etc..
If "that" stuff dies, it will decompose and and that being part of the NitrAte cycle can end up as elevated nitrates in tank, (unless you have a complete nitrogen cycle where nitrates are converted to nitrogen gas, or are exported thru other means)
Patchs turning white are "generally" coraline and can rebuild and come back without a nitrate rise...
Is this rock new..? old , just added, was it shipped, or has it been cured...?