Like mostfarming RPGs, collecting Bugs and Fish can be a valuable source of income.
These critters can usually be found on the sand amongst the ruins.
The Vampire Crab is faster and requires more ammo to stun than regular Bahari Crabs.

As such, confirm you bring plenty ofSmokepowder Bombswith you and perhaps invest in some better bombs through Auni.
As a Rare Bug, the Vampire Crab has the chance todrop 0-7 Silk Threadwhen caught.
In turn, this can be placed in aLoomto make Silk.

Otherwise, they can be a good source of gold if you manage to catch a few of them.
They sell for145 goldat the General Store, or217 goldif it is a quality Vampire Crab.
Additionally, if it is a quality crab, you could place it within your homestead as a decoration.

To do so, simply put it in your inventory and choose its designated shortcut.
Then you might move it around and place it where you like.
These require you to catch one of every Bug (both normal and star quality) in the game.

The Vampire Crab is also needed to complete theSpooky Bundle.
One of many bundles needed to unlock the Ancient Vault inside of the Night Sky Temple.