Biomass
Concept · Stellaris 4.5.2
Biomass in the Stellaris encyclopedia: Biomass is the raw organic potential generated by biological activity across the worlds of Owned Systems.
Biomass in the game's words
The encyclopedia entry as the game shows it in its tooltips; underlined words open their own entry or page here.
Biomass is the raw organic potential generated by biological activity across the worlds of Owned Systems.
It is used for constructing planetary 
Buildings and Terraforming new Colonies.
To increase:
- Grow more 
Pops
- Build Cradle of Rebirth
Source: common/game_concepts (concept_biomass) and localisation/english, Stellaris Cygnus v4.5.2 (9776).