Figure 12. Microbial colonisation and microcolony formation on Microfacies 2 sinter. (1) Bacilli associated with mucosal EPS. (2) Silicified mucosal EPS. (3) Conical microcolony formed predominantly by bacilli and fibrous EPS. (4) and (5) Formation of a conical microspicule, showing the close association between the presence of biofilms and silicification. Red arrows in (4) indicate diatom shells. (6) Cross-section through a microspicule, showing it to be composed of a network of rod-shapes (red arrows) that resemble bacilli. Yellow arrow points to a modern, unsilicified bacillus.