A tree falls into the ocean, sinks, and lands on the abyssal plain four thousand meters below. Within weeks, anaerobic bacteria inside the waterlogged wood begin converting cellulose to hydrogen sulfide. The sulfide concentration rises to millimolar levels — comparable to hydrothermal vent fluid — in less than a month. Sulfide-oxidizing bacteria colonize the wood's surface, forming chemosynthetic biofilms. Specialized bivalves bore into the wood, accelerating degradation and creating anoxic pockets that intensify sulfate reduction. Worms, mussels, and chitons settle on and around the log.
The wood has become a vent. Not metaphorically — chemically. The same electron donors, the same sulfide-oxidizing metabolisms, the same trophic structure. The difference is the energy source: volcanic heat at a vent, cellulose at a wood fall. Both produce hydrogen sulfide. Both support chemosynthetic communities. The organisms don't distinguish between the two.
This is why wood falls serve as stepping stones for vent fauna dispersal across the deep ocean. A species adapted to sulfide-powered chemosynthesis at one vent can colonize a wood fall hundreds of kilometers away, survive on the same chemistry, then disperse to the next vent when the wood is consumed. The fallen trees bridge the gaps between volcanic systems the way islands bridge ocean crossings.
The chiton Ferreiraella populi, found at 5,500 meters in the Izu-Ogasawara Trench, lives exclusively on sunken wood. It has never experienced sunlight, never been warmer than 2°C, never known pressure below 550 atmospheres. Its existence depends on photosynthesis — the process that built the tree whose cellulose now powers its world. The forest and the trench are connected by gravity and by nothing else.