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
It crawls up and down on vertical surfaces. Upon approaching it, it will sprout 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 bounce off its spikes by down-slashing. By repeatedly down-slashing, the Shardmite will retract its spikes briefly before sprouting them again, giving the player 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.

References

Fragmentita Осколик Kolczak Mite de cristal