Autocast Crystal
When a cossal dies, its cossary organ detaches from its body and crystalises.
In the majority of cases, the crystal will be inert and have no purpose beyond use as a precious stone of sorts. If the cossal in question had undergone cossary ascension and developed a mana-based skill, the skill's intention may imprint on its crystalised form and trigger when stimulated.
Cossals that develop a mana-based aqualung or levitation ability, for example, may be hunted for their autocast crystals which will activate when struck.