Figure 7. Formation of microspicular structures on Microfacies 1 sinter. (1) Upright microspicules at various stages of growth and covered with microbial cells. (2) Cluster of cells attached to the top of a microspicule. (3) Knobby texture on the uppermost portion of a microspicule with individual knobs (red arrows) equal in size to unsilicified cells (yellow arrows).