Sometimes spelled Teller and Susser. They are two of the three forms that creations in the physical world take. The other is Aether.

Often explained through the concept of The Weft and Warp.

Tellur and the material realm.

Tellur is mostly-unchanging matter. It's the stone, wood and meat that one can see and feel. Unlike Sussur, it remains in its current form without much direction from anyone. Sussur can change the form of Tellur, such as turning water to steam or wood to ash.

Sussur and Sorcery.

Sussur is where the word for Sorcery derives itself from. Sorcery is the means by which a skilled mage or sorcerer briefly harnesses aether to bring it into physical form, creating Sussurial elements. The flashes of fire, ice, lightning and more that one can see are Sussur; Aether that has been molded by a spellcaster into a denser form to serve as an element for a brief time.

Sussur remains in a summoned elemental form for only as long as the spellcaster can will it so, before it returns to its aetherial form and must be summoned into a spell once again.