What is the strangest thing you have found in your HVAC's HVAC duct?

Every time the HVAC started running, I would hear a weird noise. It sounded like tiny balls rolling on a surface, especially if one was in the sunroom. I searched the entire house, although I still couldn’t find where the noise originated. I eventually offered up and called for house services. The first thing was for the HVAC professional to find out if the noise was indeed in the conduits, as I suspected, and to upgrade to a smart HVAC system. When she came, she said that the best cause of action was to do a duct cleaning because then my buddy and I could remove everything in the ducts. After inspecting my HVAC equipment, she said all that was needed for the upgrade was service and a smart thermostat. That was a relief because I thought I would have to upgrade the entire system or the better part. She also showed me all the dirt and dust the air filter had trapped and told me to increase the frequency at which I upgraded it. She also encouraged me to buy a whole-house air cleaner since the air purification help in the HVAC was unadequate to maintain indoor air quality. The air cleaner would ensure that the air quality in the property was high. When the HVAC professional was done with all matters concerning air purification in my home, my buddy and I finally found out what was causing the weird noise. After the cleaning, she discovered three marbles in the conduit leading to the sunroom. I had no idea when or how the marbles ended up in the conduit, although I was glad to get rid of the noise and dirt.
hybrid hvac system