Lubomirskia baikalensis is a freshwater species of sponge that is endemic to Lake Baikal, Russia.

[1] Lubomirskia baikalensis is found on hard bottoms at depths between 1 and 120 m (3–394 ft).

[2][3][4] In relatively shallow water, it is bark-like, and covers stones somewhat like a carpet.

[4] From a depth of 3–4 m (10–13 ft) it starts to have branches,[4] and can reach a height of more than 1.2 m (4 ft), which is unusually large for a freshwater sponge.

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 0 °C (32 °F).