Here is the paper. It was widely discussed ... on reddit for a long time I didn't think it was real.
Ants are painted with dots that match their exoskeletons, some are painted with blue dots. The ants are observed interacting with a mirror.
I've seen this experiment mentioned as a reason why calling the mirror dot test a "test for self awareness" is flawed: a lot of people really don't like this result.
Still, the journal gives me pause. What do you think?
https://www.journalofscience.net/showpdf/MjY4a2FsYWkxNDc4NTIzNjk=