Besides fruits and milk, what other examples are there in nature where it is beneficial for a species to have some part of its biomass eaten by others so that it evolved to produce nutritious parts to be eaten by other organisms? For example, plants having animals eat their fruits as a means of transporting their seeds.
I think there are at least two philosophically different scenarios that interest me.
One is when the substance is intended to be eaten by the same species (example: milk).
The other is when it is intended to be eaten by another species (example: fruits).