The Groundium Z (Japanese: ジメンＺGround Z) is a type of Z-Crystal introduced in Pokémon Sun and Moon. It is the type-specific Z-Crystal associated with the Ground type and allows Pokémon to upgrade their Ground-type moves to Z-Moves.
Hapu was revealed to have a Groundium Z on her Z-Ring in SM104. She was first seen using it in conjunction with her Mudsdale in SM109 during her grand trial with Ash. Another Groudium Z appeared later on, among the set of type-specific Z-Crystals from which Hapu let Ash pick his grand trial prize from.