Fungal hyphae, unicellular algae, and filiform prokaryotic inclusions are the most abundant microfossils of the Cretaceous amber of Schliersee (Bavaria, southern Germany). These prokaryotes are described as Leptotrichites resinatus new genus and species, and interpreted as sheathed bacteria with similarities to the extant genus Leptothrix Kützing, 1843. However, the micromorphological and microanalytical features of this new species do not correspond entirely with those of the modern sheathed bacteria. Previous interpretations of these inclusions as filiform cyanobacteria, algae, and fungi have to be revised. Together with their numerous syninclusions, mainly fossil ciliates, testaceans, and microalgae, these prokaryotes belonged to a Cenomanian limnetic microcenosis of water bodies, such as ponds close to the resin-producing trees. Actualistic paleontological experiments reveal how these soft-bodied microorganisms could have been embedded in resins.