Basilisks are rare creatures, and usually not this large. They do have the power to turn organic matter to stone- which they do by focusing their eyes on it in a certain way and staring for a long enough period of time. Several minutes is usually enough. In the wild, they will turn things to stone for two reasons- one, as a defence, because there are bigger and meaner creatures than basilisks in this world (and basilisks are actually kind of slow on the ground), and two as a way of capturing food. Their prey gets turned to stone slowly from the outside in, so a quick blast will only solidify the outside, leaving plenty of edible meat inside.
This has been a presentation of Hinterland Who’s Who. *cue music*