Fig. 5

Pleistocene stromatolite (specimen LBA-9b). a Polished section of a portion of the specimen, with laminae identification beside the sampled points (A and B refer to the types of laminae described in the text); b and e Photomicrograph in optical microscope; b The two types of laminae. Note the gradual passage from type B to A and the sharp ending of type A, which at places is highlighted by a thin micrite lamina; c and d Photomicrographs from scanning electron microscopy; c Detail of lamination. Note calcite tubes between the large-crystal laminae (red arrow); d Detail of calcite tubes in the type B laminae; e Detail of coalescent bush-shaped bodies consisting of calcite filamentous bodies, likely from cyanobacteria, in a type B lamina