It was found during restoration work at the Church of the Holy Sepulchre in Jerusalem, which is built on the site believed to be where Jesus' tomb was.
It was located inside the Edicule (above), a small chapel marking what's thought to be the exact site of Jesus' tomb.
It's thought the slab (below, bottom picture) hasn't been since 1555 AD.
Scientific analysis has begun to try and get a better idea of whether Jesus' body really was laid on the slab or not.
The Church of Holy Sepulchre is one of the most significant pilgrimage sites for Christians and is a major place of worship for Catholic, Armenian Orthodox and Greek Orthodox believers living in Israel.
Work began last year to restore it after it was shut down over safety concerns.
The Church was built by the Christian Emperor Constantine in 325 AD before Muslim Caliph al-Hakim destroyed it in 1009.
Crusaders rebuilt the Church before it was gutted by a fire in 1808 and partially restored.
It was then struck by an earthquake in 1927 meaning it required more repairs which are now taking place.