Shardmite

"Feeds on crystal dust and uses crystallised spines to protect itself from danger. I don't find this creature particularly noteable [sic] or interesting. It should learn to fly, or breathe flames, or sing hauntingly. Anything to justify its existence."

Shardmites are enemies in Hollow Knight. Formerly used in Crystal Peak's mining operations, these creatures now wander around on walls, feeding on crystal dust.

Behaviour and Tactics
Crawls up and down on vertical surfaces. Upon approaching it, it sprouts long crystal spikes from its shell. While those spikes are extended, it is invulnerable. By attacking quickly, it can be taken off guard and killed before it sprouts its spikes.

It is also possible to Nail-bounce off its spikes by down-slashing. With repeated down-slashing, the Shardmite retracts its spikes briefly before sprouting them again, giving the Knight a chance to get in a hit between spikes while keeping distance.

Location
They can only be found in Crystal Peak, mostly across the northeast part.