Signals propagate along wires, 'operating' upon a wire when the target wire identity of the signal matches the identity of the wire cell. Some signals can cause a wire to grow. Other signals can change an existing wire cell's identity, direction or even kill it. At every clock tick there is a small random probability that a wire will corrupt a signal, or delete it, or spontaneously create a new signal. If both minor inputs have signals, only one will be accepted using clockwise priority.
All wires age, starting from the time when they are first created.
When a wire reaches the end of its life, it dies, and the cell returns immediately back to the empty state. Wires cannot be grown to join another wire unless the growing wire tip, or a wire cell that is in the way, has the special 'terminal' identity. This allows the wire loops to be fairly robust, so that they cannot easily be disturbed by the signals on other wire loops, yet still allows wires to connect to themselves to form loops. Two wires cannot both grow to the same destination cell at the same time. If this is attempted, neither wire will grow.