As the logic of biomass from all of the plant based material is that it is fermented, I would like to propose that the same can be done with animal products, like all of the meats as well as rotten flesh, could be done in the same manner to produce biomass. It’s all still a biological material, and if you want to tier it, you could require that it all be fermented into rotten flesh and then into biomass. This would allow more meaningful use for rotten flesh in the mod.