In the next chapter it will be explained how the metazoans are evolved. First, however, we will follow the development of a simple metazoan. This will clarify how the different parts of the model are put together to result in a the simulated development of a multicellular ``organism''. Additionally, it may evoke some intuition about how the metazoan developmental program is coded in its genome. This may help the reader in understanding what happens during the metazoan evolution.
In order to obtain a simple example organism, an evolutionary search was set up selecting for metazoans that developed stable cell types3.1. From this run a nice example was chosen. The development of this example is described in detail below.