In the deep sea the COMARGE project has studied the biodiversity patterns along and across the Chilean margin through a complexity of ecosystems such as methane seeps and oxygen minimum zones reporting that such habitat heterogeneity may influence the biodiversity patterns of the local fauna. Seep fauna include bivalves of families Lucinidae, Thyasiridae, Solemyidae ("Acharax" sp.), and Vesicomyidae ("Calyptogena gallardoi") and polychaetes "Lamellibrachia" sp. and two other polychaete species. Furthermore, in these soft reduced sediments below the oxygen minimum zone off the Chilean margin, a diverse microbial community composed by a variety of large prokaryotes (mainly large multi-cellular filamentous "mega bacteria" of the genera "Thioploca" and "Beggiatoa", and of "macrobacteria" including a diversity of phenotypes), protists (ciliates, flagellates, and foraminifers), as well as small metazoans (mostly nematodes and polychaetes) has been found. Gallardo et al. (2007) argue that the likely chemolithotrophic metabolism of most of these mega- and macrobacteria offer an alternative explanation to fossil findings, in particular to those from obvious non-littoral origins, suggesting that traditional hypotheses on the cyanobacterial origin of some fossils may have to be revised.