1 Corinthians 10:4
...For they drank from the spiritual Rock that followed them, and the Rock was Christ.
Rocks are usually pretty inanimate and keep to themselves. Paul points out here, however, that the Israelites had a Rock which followed them through their desert wanderings: Jesus Christ, the Lord!
Jesus explained to a few disciples on the Emmaus road that the entire Old Testament pointed to him (read HERE.)
Paul is not saying that rocks are God or that God is a rock, or even that God is in the rocks. Paul did not find Jesus in the rocks as it were. It's not a magic 3D picture that requires a keen eye and patience to reveal the true picture. Jesus is the fulfillment of the Old Testament and the main character to which the whole narrative expounds. He is the protagonist. He is the hero.
(on a side note: realize that what the early church referred to as the Bible was the Old Testament. The New Testament was not written or compiled yet as it was still being written and copied by the early churches to whom the letters were addressed)