Perhaps comparable to the Limniads, these Spanish water spirits live in a
lake on the summit of Convagnum in Catalonia. If anything fell into this
lake, there would be an awful unrest in the lake, and the water in it was
dark and fathomlessly deep. The lake demons kidnapped humans and used them
as beasts of burden, especially children whose parents carelessly wish for
this to happen. These unfortunates are kept for at last seven years before
being released to the mortal world once more.