I found this on the roof of the hotel. It is milky white. What is this? Could it be a camera?

Sorry, I'm not sure what you mean by "thing", because it depends on its specific appearance, location and surrounding environment.

However, if you suspect that it may be a camera, you can consider the following suggestions:

1. Observe the appearance: If this thing has the characteristics of lens, circuit board and battery, it may be a camera. Meanwhile, if it has an infrared transmitter or receiver, it may be an infrared camera.

2. Look for installation marks: If this thing is a camera, it may have been installed on the roof of the hotel or somewhere nearby. You can look for installation marks, such as brackets, screws, etc.

3. Check the surrounding environment: If this thing is a camera, it may be installed in the monitoring area. You can check whether there are similar devices or cameras around.

4. Use professional equipment: If you are still not sure what this thing is, you can consider using professional equipment, such as an X-ray machine or an infrared scanner, for further inspection.

Finally, if you have any questions or concerns, I suggest you contact the hotel management or local police in time to ensure your safety and privacy are protected.