A tiny spark of flame that acts as a pyrausta's heart beats within its chest. Whenever a pyrausta takes cold damage, including damage from environmental cold, its little heart stalls. It loses its fast healing and breath weapon, gains the staggered condition, and takes 1 point of damage each round. This continues until it is exposed to a source of flame that would normally deal fire damage or until it successfully uses its spark spell-like ability to reignite its heart (doing so requires a successful DC 11 concentration check because of the ongoing damage).