Grodan comes in graduated sizes. Seedlings started in cubes are easily trasnferred to blocks and then onto slabs, if desired. Stonewool products are made from basalt rocks and chalk, which come from the Earth. Mimicking Mother Nature's production of "angel hair" during volcanic activity, the Grodan Stonewool manufacturer heats rocks to 1600° C, to create lava. The lava is blown into a spinning chamber, which makes fibers similar to cotton candy. The fibers are packed into mats, from which Grodan cubes, blocks and slabs are cut. Small tufts of fibers are also produced and bagged as "Stonewool granulate". The products make excellent use of natural resources: one cubic yard of rock becomes 37 cubic yards of agricultural 'rockwool'!