A plant grows with vigour.

The model itself operates at three time scales: i) a within patch foraging scale (one tick of the intragenerational clock); ii) an intragenerational patch-to-patch movement scale (n ticks of the intrageneration clock equal to 1 tick of the intergenerational clock); and iii) an intergenerational evolutionary scale (G ticks of the epochal clock), as depicted in Fig 2 .

Entering the tunnel, we pass a small shrine above our heads which contains a statue of St Barbara, the patron saint of tunnellers. It is traditional to have such shrines on every tunnel site.

In old cultures, contents of cells without rhizopodia can turn dark and act as resting (cyst-like) stages.