Verrucaria nigrescens 1, Gewone stippelkorst, Saxifraga-Jan van der Straaten Gewone stippelkorst  Close up of the crust shaped lichen Verrucaria nigrescens (dark grey) on basalt, Streefkerk, South-Holland, Netherlands : basalt stone, color, colour, crust, Dutch, Holland, horizontal, lichen, Netherlands, Verrucaria nigrescens