Based off the fact you need to heat sand to make glass.
Exposing a sandygast to a firestone allows it to evolve into Polaflect! While one may assume being made out of glass can lead to extreme brittleness, make no mistake. The haunted sand particles controlled by the intertwined souls of many have allowed it to form glass stronger than no other, taking on even the most brutal of damage.
The shells that were once entrapped by sandygast have now formed an amalgamation of mass underneath the Pokémon, keeping it sturdy from ground attacks.
Signature ability: Strong Foundation – This Pokémon takes 1/2 damage from ground attacks
by super_butter_nut