When a planet with a Honeycomb is focused on Industry, all industry focused Supply connected planets gain 0.5 Industry per Population.
The Honeycomb is a planet that was prepared as a stash by the Builders in ancient times. Almost all other planets in surrounding systems were stripped of valuable materials and then dismantled. The materials were sorted and stored separately in gigantic tubes embedded into the planets crust. The sprectrum ranges from rare and valuable elementals to hard to produce molecules and a vast array of energy sources. What the Builders wanted to create with this treasure or why they didn't use it in the end, is unclear.