Filamentous micro-organisms in Upper Cretaceous amber (Martigues, France)

► We document for the first time micro-organisms in Santonian amber from Martigues. ► Various filamentous prokaryotic and eukaryotic inclusions are described. ► The distribution of the filaments is related to the type of amber. ► The filamentous organisms have grown in the fresh resin before its solidification. ► The study reveals a new and totally unknown fossil resinicolous micro-world.