stro·mat·o·lite 
(strō-mătl-īt′)
(strō-mătl-īt′)n.
A usually rounded or columnar sedimentary structure consisting of alternating layers of carbonate or silicate sediment and fossilized microbial mats, produced over geologic time by the trapping, binding, or precipitating of minerals by groups of microorganisms, primarily cyanobacteria.
[Late Latin strōma, strōmat-, covering; see STROMA + -LITE.]
stro·mat′o·litic (-măt′l-ĭtĭk) adj.
stromatolite