Permian Basin coral fossil rock?

[bprewit]

Its very common to find fossilized rocks from coral reefs around where I live. Most that you see are large mollusk fossils and others are just sedimentary rocks. I am wondering if these could be used as base rock in reef tanks? I dont suppose anyone on this board is a geologist? Just curious

[GaryP]

Yes, they are basically just limestone. However, they lack the porosity that we normally look for in live rock. The pores have been compressed by geological activity. These pores are what make live rock unique. They provide the spaces needed for a high degree of biological activity.

The other alternative is Tufa rock, which is basically terrestial limestone that hasn't been compressed. Its "younger" in geological terms. It is the result of a coral reef left dry by volcanic uplifting or changes in sea level.

Gary