CT scanners can visualize the interior of stone blocks to locate fossils for the purpose of extraction planning but obviously you're limited to the dimensions o

CT scanners can visualize the interior of stone blocks to locate fossils for the purpose of extraction planning but obviously you're limited to the dimensions of the scanner. They're also used to image the inside of fossilized eggs. Ground penetrating radar can be used to visualize fossils but the conductivity of the material greatly impacts resolution (it's poor no matter what) and reach. Low-conductivity materials can be imaged up to tens of meters, high-conductivity materials you're lucky to get one meter. There are other methods for imaging that can penetrate further but I don't think they have the resolution to be useful (think: "there's an oil deposit down there" not "there's a body").