Insect & animal colonies...

Colonies... The game I described earlier (with Aukje) has a system similar to colonies. A mass of individuals. While my focus is from the 'individual to other' interaction and not the wider 'many individuals as single organism' idea colonies could still provide an interesting framing device/ context.

Ants
Ant colonies are often used to portray ideas of individualism in popular media (Antz, A bug's life, Adam Ant). It might be because they're a colony type insect that is very common, and the common ant is not harmful. They can be quite entertaining to play with.

Bees
Not so friendly, not quite as often used. But also exhibit some amazing collective behaviors.