by Christoph — Among the Alphaproteobacteria, a number of species from phylogenetically distantly related orders are known for forming rosettes during growth. Despite commonalities, they all have their own peculiarities when it comes to the first cell‑cell contact(s) during "rosetting". Phaeobacter inhibens (order Rhodobacterales) cells attach to each other by their "sticky ends" at one pole...
by Christoph — I like to imagine that microscopists in the late 19th century who looked at water samples were happily surprised when they saw organized structures of cell clusters in the whole tangle of protists and bacteria, which they then liked to call "rosettes" because these were structures known from botany. And on closer inspection, it turned out that some of them were actually bacterial rosettes…
by Christoph — I dare say that every biologist was blown away when they, a decade ago or so, first saw pictures of spherical rosettes that choanoflagellates can and readily do form. Is this emergent multicellularity? Skilled microscopists had long been aware of such "rosettes" among (some) bacteria, but they never made it into the canon of bacterial shapes as they only form under certain growth conditions.
