SynStromatolite Abstract Stromatolites are pillars of mineralized biofilm laid down by communities of photosynthetic bacteria. The dominant visible evidence of life on Earth for billions of years, stromatolites now only form in environments like hyper-saline water that exclude multi-cellular animals. Like tree rings, the records left in the layers of ancient stromatolites can be used to infer information about their environment like hypersalinity (Zhu et al., 2021) or fact that the Earth was spinning faster 2.5 billion years ago and an Earth year was 435 days instead of 365 ([(Vanyo & Awramik, 1985)(#vanyo1985)]). A synthetically engineered consortia that mimics the layer formation ability of stromatolites enables the development of low cost self-powered biological biosensors that record a time series of their outputs as mineralized biofilm layers. [Combining with existing water quality biosensors can help address water quality health problems in resource constrained areas] As a feasibility demonstration this projects engineers a two-strain Esceheriichia coli consortium that that use quorum-triggered curli amyloid secretion to lay down biofilm layers with enhanced mineralization capabilities. The projects’s central hypothesis is that separating biofilm generation and reporting responsibilities across multiple strains will be superior to trying to put all the functions in a single organism in terms of growth (as measured by OD900 curves), biofilm production (as measured by a Congo Red depletion assay), sensor signal strength (as measured by 590nm absorption), and mineralization (as measured by a calcium depletion precipitation assay). The project also lays out a road map to further develop this consortia into a deployable biosensor recorder platform.