Tanyenn is a luminescent algae that grows in the Sea of Songs. It is a very useful and versatile plant to the Maerum and Alatien. Apart from its use as a convenient light source, it attracts small fish which can then be caught for food - while larger, predatory fish like the Snapjaw tend to avoid the light that Tanyenn emits. There is a suggestion that a lack of Tanyenn in the diet of the Alatien may be responsible for their weakening wings. The Maerum have a particular, very unusual use for it; if a human (or presumably any other sentient 'landwalker') ingests some of it with a specific type of pearl and some of his/her own blood, that individual is then be able to comprehend the language of the Maerum, possibly through some form of telepathy.