Development and maintenance of coral reef ecosystems rely on daily micro-biological activities of healthy corals. Although a comprehensive understanding of coral biological properties as well as factors negatively affecting coral growth are essential to conserve existing corals, the current lack of a tractable culture and experimental platform has delayed establishment of such a knowledge base. Here we show a highly versatile experimental platform, coral-on-a-laboratory dish (COOL), allowing long-term culturing of various corals in Petri dishes and maintaining their wide range of biological properties. Under optimized conditions, coral microcolonies (5 mm x 5 mm fragment) of Pocillopora damicornis were cultured for several months in dishes with high survivorship and distinct growth. COOL has been used to maintain at least 3 other small polyp species (A polyp 1-2 mm in diameter), namely, Acroporidae family, Acropora tumida, the Pocilloporidae family, Stylophora pistillata, the Poritidae family, Porites lobata, and one larger polyp species (A polyp 5-10 mm in diameter), the Merulinidae family, Favites pentagona for > 2 months with 100 % survival rates and apparent growth. COOL was shown to be applicable to a variety of biophysiological and ecotoxicological studies, including coral-algal symbiosis and impact assessment of pollutants at cellular-level resolution. This simple but powerful experimental platform will greatly advance coral studies.