Reproduction

 is evolved behavior of cells that allows a sufficiently large cell to split into two or more copies of itself.

Multi-cell reproduction
Multi-cell reproduction requires two or more cells of the same species to reproduce. This type of reproduction most commonly manifests as a cell which explodes upon contact with another instance of itself, but quickly re-forms as multiple cells.

Single-cell reproduction
Single-cell reproduction requires only one cell to reproduce. It is most commonly manifested as cells which move faster as they accumulate more resources until they split in two.