A composted mass is formed into a shape, e.g. a pebble shape, which may be both compact and porous. The composted mass comprises: (a) the shape consists of mature compost with a maximum moisture content of 20 %, and a minimum organic content of 30 %; (b) the grain size of the compost used does not exceed five times that of the smallest grain; and (c) the bio-degradable additives are included in the material which enhance the utility and physical integrity of the end-product.