Crystals range from small to large
They can be less than 6mm up to the size of a golf ball! Calcium oxalate crystals, the most common crystal ( ~80%), come in many shapes and sizes because these are chemical crystalline materials. The most common crystalline materials found in crystals are calcium oxalate, calcium phosphate, uric acid and struvite.
It is not uncommon for a crystal to contain more than one crystalline component. Noncrystalline materials found in crystals include proteins and blood. Calcium oxalate crystals come basically in two varieties, calcium oxalate monohydrate and calcium oxalate dihydrate.
Below are just a few pictures of crystals secured from various websites which will document the enormous variations in shape and size of the crystals.