Another rock question

[benwildog]

I have had freshwater tanks for years, and my current tank which I am disassembling has a large rock in it with lots of life. Can this be used in the saltwater tank I am setting up? I have lots of previously live rock from my friends old saltwater, but am curious if this rock is usable.

 

[elfdoctors]

I wouldn't use the rock from your freshwater tank. You don't know what minerals will leach out.
The old live rock is fine. It is now baserock. You should get some new pieces of live rock to seed the base rock and make it live.