Mictyris is a genus of brightly coloured crabs, placed in its own taxonomical family, the Mictyridae.

[1] It inhabits the central Indo-West Pacific region.

These crabs congregate on mud flats or beaches in groups of a few thousand, and filter sand or mud for microscopic organisms.

This is done in wet sand, and they dig in a corkscrew pattern, leaving many small round pellets of sand behind them.

The genus contains eight species:[1][2][3][4] The predictable behaviour of these crabs has led them to be used in experiments in a form of billiard ball computer.