Chinese scientists have published an analysis of a curious substance on the moon which generated widespread interest following its discovery by the Yutu 2 rover last year.

The discovery was made by a Yutu 2 drive team member in July 2019, during lunar day 8 of the rover’s mission, which is part of China’s Chang’e 4 mission to explore the far side of the moon. A report by Our Space, a Chinese-language science-outreach publication, revealed the discovery on Aug. 17 and described the substance using the term “胶状物” (“jiao zhuang wu”), which can be translated as “gel-like.”