Rock In Tank?

I was thinking of using some lumps of rock in my tank that my friend had in his cichlid tank ,These are white/grey in colour and full of holes i will post a pic of a similar one.
Some people have said i can use and some have said can i use this and some have said i cannot
and if so will i have to boil it ??
Any help would be appreciated.

Thats known as Coral or Ocean rock. Yes you can use it in your tank, remember it will raise the Ph of your water. Ive never boiled coral rock, just washed it to remove the dust etc.

No reason not to imo