Lubomirskiidae

Lubomirskiidae is a family of freshwater sponges from Lake Baikal in Russia, endemic to the lake, though there are unconfirmed reports from Lake Jegetai-Kul in the Western Sayan, along with the Bering Sea and the sea surrounding Kamchatka.

==Description== Lubomirskia baikalensis (the most abundant species), Baikalospongia bacillifera and B. intermedia are unusually large for freshwater sponges and can reach or more. These three are also the most common sponges in Lake Baikal. Lubomirskiid sponges are perennial, and may grow in multiple ways; they may encrust their substrate (cortical growth), or grow up into either a form low to the substrate (cushion-shaped) or a tall branching one. Growth is slow, around per year. Their skeleton is typically "multispicular alveolate-reticulate". Their megasclere spicules consist of spiny oxeas and strongyles, and they do not develop microscleres. Spongin is present throughout their body, such as the tips of their spicules, though this protein may be absent in some parts of the body. Going through a grade of Lubomirskia-Baikalospongia-Swartschewskia, the ectosomal skeleton ranges from "tufts" of spicule "from the primary fibres" to "hard and well-developed", while the choanosomal skeleton ranges from regularly anisotropic to "sparsely developed". Using this same grade, the consistency of the sponge's body ranges from elastic to fragile, though individuals of all species range from rigid to soft or flabby.