how did you bring it back: in a bag dry, cooler with water, how? thats an important Q. if anything cure it

IDK bout those, i would think of it as liverock n cure it, just to be safe

how long has it been dry?

A note on "liverock" - I havn't heard anyone use the term regenerated yet so i'll coin the phrase . as live rock goes, it's harvested and put into tanks to allow whatever died from the ocean to the tank to "cure" off -basically rot off [man it stinks] from there you bring it home [wet] cycle it into your tank, and it has good bactierias, little critters, corals, mushrooms, worms all kinds of cool, good and bad stuff, think of it as a jump start from one environment [the worlds oceans] to another [your livingroom]
That being said, anything porus you put in the tank will eventually become "live" as bactierias and the like settle in and take up home keeping on them - so if your coral has been dry for quit awhile, i think you could boil it and I would soak it for a day or so in a bucket of salt water, just incase some crude comes out, then place it in the tank and watch it "regenerate" again
I have half purchased actual "live rock" and half dried coral rock that is becoming live as time passes - -hope this helps - -read read read , welcome to the addiction !!!!!!!

actually if my reading and all the comments here and there on this site are precise..that rock will sooner or later become "live" its just bound to because bacteria are bound to call it a home sooner or later..I THINK. lol