Oumuamua is worth looking at for scientific value even it is only an anomalous interstellar object.
Harvard researchers have calculated that unusual speedup and movement of Oumuamua indicate that it could be solar sail. It might weigh only 100 to 300 kilograms instead of a solid comet-like material. If it was comet material it would weigh one million to ten million tons. If it is a solar sail it would be evidence of a civilization of technologically capable aliens that sent out a solar sail probe millions of years ago. We have only just had a few smaller solar sail probes.
In 2010, the Japan Space agency launched IKAROS. It has a diagonal spinning square sail 14×14 meters and made of a 7.5-micrometre (0.0075 mm) thick sheet of polyimide. The polyimide sheet had a mass of about 10 grams per square meter.