Grimmia orbicularis is a saxicolous moss species. In 1990 it was discovered on free standing, concrete bunkers in the western part of the Netherlands. These bunkers were built in 1939 as part of the Dutch war defence. The species was growing on south-west to south-east facing, slanting roofs. Nearly all of the plants were fertile, growing together with other species of the Grimmietum orbicularis association.