PURPOSE: To obtain at least one surface with a material layer being fixed and held on an embankment element and promoting the growth of plants on the embankment element for stabilizing or supporting a slope.

CONSTITUTION: A prismatic body 10 has at least one self-supporting side wall 2 and has other side walls 3, 4 formed by a load-bearing single-piece mat 8 which is provided with through-passages 7 and also encloses the self-supporting side wall 2. The self-supporting side wall 2 and the other side walls 3, 4 enclose, with the interposition of a material layer 6, a core 9 consisting of a humus-like composition, and the end parts of the mat 8 are connected to one another and may be suspended on a bearing element 12. Accordingly, the embankment element can be factory-made previously, and can be implanted previously or can be greened previously, and can be transported to the building site as a finished product.