The red rain microbes, which caused red rain phenomenon in Kerala, India, exhibit many characteristics much different from conventional microorganisms. Previous study indicates that these microbes are possibly of extraterrestrial origin. Their ability to multiply at extreme high temperature of 300°C and the unusual autofluorescence of their biomolecules are some of their extraordinary properties. Their molecular composition is yet to be identified. In this paper we report the growth pattern of these novel microbes at temperatures below 100°C as a minimal approach to show their biological nature. Automated turbidity measurement of the cell culture indicate standard microbial growth curve. Increase in the cell population is faster at higher temperatures. Details of this investigation and results are discussed.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.