So there's this book called Fantasy Genesis that is great for creating new species and testing yourself. It's also based on dice rolls to choose the various bits and pieces to an extent.
I hadn't actually used it until today, when I got bored and did some rolls.

I got these words: Mantis, Frost, Razor/Knife, Glass/Crystals

The Mantem is a unique species of mantid native to the Arctic Circle. Their exoskeletons appear to be made of stone or gem, and possess the corresponding strength. Their delicate-appearing limbs are coated with icicles and frost which will either break off or impale prey, though as of now the Mantem's preferred food is unknown. The Mantem is often surrounded by a faint "mist" or freezing fog which helps it to blend in to its icy surroundings.

This example is supposed to be an Obsidian Mantem, but the "types" of Mantem span the entirety of all known gemstones and stone types.