Fig. 1 Exponential hyphal growth enables an ef fi cient biological Ponzi scheme for resource acquisition. Each block represents a unit volume, containing external resource (white compartment) comprised of 30 units of C (three red circles) and one unit of N (one blue cross). Hyphae (grey region) consume these resources as they grow, and can also translocate resources throughout the colony to fuel new growth. If the time taken to exhaust the local supply of N and C is T and mT respectively (illustrated here for m ¼ 3), and over time T the colony can grow by a factor of 2, the fraction of the colony that has exhausted the local supply of N and C reaches a constant 2 (cid:1) 1 and 2 (cid:1) m , respectively, after an initial period of length T and mT , respectively. If unicellular organisms and hyphal organisms take up N in the same way and need the same amount of carbon for each unit volume of growth, each growing cell in a unicellular colony would need to take up 17.5 C for each N instead of 10 C for each N, and would therefore need to synthesise a correspondingly larger number of C digesting exoenzymes.