Cells absorb red food particles, grow fat and divide. The daughter cells repel, pushing each other further into free space. At a critical density of food particles, this leads to them absorbing enough to divide right again. The new fission products are pushed even further into the food field, so they, too, divide again. There is an explosive replication, everything is full of cells.
The food is used up. The cells die off. Only at the bottom right (where there is more food) and perhaps somewhere else, a few survive. Now and then, they obtain a piece of food, enough to stay alive and perhaps even to divide. Meanwhile, in the cell-free space new food accumulates, until the critical density is reached...
