This is a piece of burnt leaf from water wisteria, burnt underwater.
The white discoloration is dried and wrinkled from prolonged exposure to the resonance frequency that breaks \(NO\) bond in \(NO_2\), nitrites at \(299.792\,Hz\). Freed oxygen radicals burnt the leaf as if it was too dry under the sun.
Removing nitrites, limits unwanted algae boom but too much removed, burns.