Nature is the proof of dialectics. It's easy to visualise the dialectic between a bee and a flower, with both of their lifecycles intrinsically dependent on the other and their material/social role. The bee exists through its metabolism, collecting pollen/nectar and supplying them to its complex hive society for use as honey. Its body evolved sacs to carry even more of it. If a flower can't self-pollinate, it has evolved to attract pollinators. It will draw from its dialectical relationship to sky/soil and synthesise new chemicals, it will evolve its body to look like the female version of a particular wasp so the males try to mate with it, it will find new ways of attaching more pollen to each bee. As long as the material conditions exist for the flower and the bee, their metabolic interaction with them will sustain and develop their dialectic with each other and their individual lives as a result of it. Take away the flower and the bee no longer exists, take away the bee and the flower no longer exists. They are structurally interdependent and no individual bee can decide to take up farming or accounting instead because the material conditions don't allow for that.

There's also climate change, the organs of the human body, predators and prey, rocks and rain forming waterways over time, and the good ole Heraclitus' "No man steps in the same river twice, for he is not the same man and it is not the same river." with a breakdown of all the ways those two things have changed as a result of their other dialectics in-between swimming sessions.