Long overlooked, sponge grounds are now known to create habitats and support high biodiversity, with its associated benefits. Some of these variously dense deep-sea sponge aggregations are formed by hexactinellids, which can occur on both soft and hard substrates. Notwithstanding their ecological importance as occasional habitat framework building taxa, only 33 species in this Class were reported from the entire South Atlantic until now. Most of this knowledge was gained from studies conducted at the eastern South America continental slope. Here we report on the finding of a hexactinellid sponge garden by the Shinkai 6500 manned submersible in the Rio Grande Rise, a prominent topographic feature of the deep SW Atlantic. This is the first sponge garden worldwide found to be dominated by the stiff, often dichotomously branching Sarostegia oculata, which occurs as densely as 5+ individuals per square meter. This sponge, of uncertain familial allocation, seems to always carry epibiotic zoanthids, thus mimicking the 3D framework of actual coral gardens.