Water terastal cristal onix by EVcreation on DeviantArt

Crystal Onix Theory : r/pokemonanime

Onix (Crystal) by Xroser on DeviantArt

095 Crystal Onix by UnusualPotato1872 on DeviantArt

OnixWaterDragon - Hobbyist, Digital Artist

Cristal Stonix by Urbinator17 on DeviantArt

Explore the Best Crystalonix Art

A cute crystal onix by DangoTheCreative on DeviantArt

Onix #095 by womack90 on DeviantArt

Theory: the crystal Onix from the anime was a water typed Terastallized pokemon : r/pokemon