rock is a kind of material & stone is hard ->  rock is a hard material  rock is a hard material & granite is a hard material -> microbes is a mean of stone granite is a kind of rock  granite is a kind of rock & granite forms from cooling magma -> using is a mean of stone that action from heat quarter granite is a kind of rock that forms from cooling magma  igneous rock is a kind of rock & igneous rocks are formed by magma cooling -> igneous stone is a mean of stone that is formed from clay heat igneous rock is a kind of rock that is formed from magma cooling  granite is a kind of rock that forms from cooling magma & igneous stone is a mean of stone that is formed from clay heat -> granite is a kind of igneous rock