Footage shows onlookers watching in confusion as a single, perfectly rectangular cloud mysteriously appears in the clear sky on a sunny day.

The oddly-shaped '2D' cloud was filmed above Zibo, Shandong Province, China, on Tuesday, November 26.

Spectators, including Mr Zhang, a teacher at Zhangdian Middle School, observed the cloud for nearly 20 minutes, noting its slow drift and sharply defined edges.

The video appears to have been filmed outside the school, with several students looking up at the sky in amazement and trying to capture the rectangular cloud on camera.

One observer said: 'It looked like a magic carpet.'

However, experts have since clarified the mystery.

The Zibo Meteorological Bureau staff confirmed that it was not a natural phenomenon but likely a contrail— a cloud formed by aircraft exhaust condensing in cold, high-altitude air.

Meteorologist Hu Xiao stated: 'This is simply an aircraft contrail.'

Authorities explained that the isolated cloud's unusual appearance may have been caused by unique atmospheric conditions in Zibo that day, which prevented it from dispersing as quickly as typical contrails.