Lubomirskia baikalensis is a freshwater species of sponge that is endemic to Lake Baikal, Russia. It is commonly called the Lake Baikal sponge and it is the most abundant sponge in the lake, but all the approximately 15 species of sponges in the family Lubomirskiidae are restricted to Baikal.Paradina; Kulikova; Suturin; and Saibatalova (2003). The Distribution of Chemical Elements in Sponges of the Family Lubomirskiidae in Lake Baikal. International Symposium - Speciation in Ancient Lakes, SIAL III - Irkutsk 2002. Berliner Paläobiologische Abhandlungen 4: 151-157.
Lubomirskia baikalensis is found on hard bottoms at depths between .Kaluzhnaya; Belikov; Schröder; Rothenberger; Zapf; Kaandorp; Borejko; Müller; and Müller (2005). Dynamics of skeleton formation in the Lake Baikal sponge Lubomirskia baicalensis. Part I. Biological and biochemical studies. Naturwissenschaften 92: 128–133. In relatively shallow water, it is bark-like, and covers stones somewhat like a carpet. From a depth of it starts to have branches, and can reach a height of more than , which is unusually large for a freshwater sponge.Belikov; Kaluzhnaya; Schröder; Müller; and Müller (2007). Lake Baikal endemic sponge Lubomirskia baikalensis: structure and organization of the gene family of silicatein and its role in morphogenesis. Porifera Research: Biodiversity, Innovation and Sustainability, pp. 179-188. On rocky grounds at depths of the branching form is particularly common and may form "forests". Some specimens have been observed to be non-sessile, being fragments originating from sessile stands which have broken free and drift above the soft benthic sediment.
This sponge is in mutual symbiosis with a green dinoflagellate, making it green in appearance. Okadaic acid produced by the dinoflagellate assists the sponge to survive when Lake Baikal is iced over in winter, and the water temperature is close to .
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External links Picture of this species