I recently purchased a home in St. Louis. There are decorative rocks along the walkway leading to the front door. I'm pretty sure these are man-made rocks. They are getting holes in them and are starting to look like big round sponges. Do I have to replace them, or can I paint them?
You could paint them with any exterior masonry paint. However, think about what comes next: repainting. You'd probably need to repaint them every 2-3 years due to exposure to weather.
Your best bet is to replace them with new rocks, or with another decorative entranceway border.