Densities data measured from abundances of inventoried species on the hydrothermal edifice Eiffel Tower (Lucky Strike vent field, Mid-Atlantic Ridge), during Exomar (2005), Momareto (2006) cruises. Seventeen sampling units were selected to represent variate mussel assemblages on the edifice. Details on the sampling method and biodiversity analysis are published in Sarrazin et al. 2015 (https://doi.org/10.1016/j.dsr2.2015.04.013) and Husson et al. 2017 (https://doi.org/10.1016/j.dsr2.2016.05.028)