I admit to knowing nothing about SP-B, i am not going to shy away from commenting on diagrams that dont make visual sense to me however, and this is one such.  From a team of highly published and well recognized names in surfactant biology is a paper linked here which has a model suggested for SP-B. When i look at the hexameric original turquoise-blue ribbon diagram transparent behind their AFM image i am forced to ask myself…. why is a hexagon arrangement logical to them here when clearly the structure is a five sided polygon — at least in the context of this particular micrograph and diagram. This doesn’t make visual sense, no matter how much sense it makes to them scientifically.

Below. both background greyscale diagrams are theirs: on the left one i have superimposed a similarly colored regular hexagon pointing each of its angles to their blue ribbon molecular diagram which they propose to be SP-D (and to this particularly, i cannot comment )On the same image from their publication (copied and pasted on the right) i have drawn in a slightly irregular pentagon, which in my humble opinion makes more sense than their hexagon. (bottom image is  photoshopped to accentuate luminous areas. Still no real definition of a hexagon, certainly it is more complicated and nothing about the images suggests hexagon.