There are thousands of these Dogu figures in Japan, but having lots of them doesn't help us to work out what they're for. We know that the ancient Japanese were fond of them for a very long time - the newest figures are about 2,300 years old, and the oldest are more like 10,000.
To add to the intrigue, some of them seem to be wearing goggles or glasses. Others have enormous eyes, as aliens often do in abduction stories. What do they depict? What were they used for? We simply don't know.