This communication investigates the recent and marginal scientific and agronomic interest in earthworms (or "lumbricids"), which paradoxically accounts for the first animal biomass of the globe. After giving some historical points of reference about earthworms' quite recent scientific knowledge-building - thanks to soil scientists and biologists' works -, we present the manner in which the earthworms and their agricultural and ecological functions are valued today amongst groups of farmers linked to "conservation agriculture practices". This second part is built on sociological observation and interviews amongst those "conservation farmers", at work as well as communicating on their soil conservation practices (no-till, direct drilling, etc.). By doing that, we aim at describing how the earthworms, conceived as "intermediary objects" and "spokesperson" of the much larger soil biology, allows for those practicians to make strongly hold together production and environmental challenges in the agriculture they're developing... instead of opposing those stakes as it's usually the case. FRUCTIS