| On this protected and shady niche on the roof of Millington Hall, one can see the process of bare rock being slowly converted to a more livable habitat through the formation of soil. In this case, the soil pioneers are the mosses. |
| Organic matter comes both from mosses that have died and decayed as well as from leaf litter blown by wind onto the rooftop. Seed plants can begin to take root in the newly formed soil. In the picture above, grasses (monocots) are growing, while in the picture at right, one can even see the first dicot taking hold. | 
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