Xenophoridae

Troschel, 1852 (1840)
The Xenophoridae is a small family of mesogastropods found on the continental shelves and slopes of most tropical and temperate regions of the world. They are especially notable for their peculiar habit of fixing foreign objects (shells, pebbles, etc.) to the dorsal surface of their shells, and thus they have earned the popular name of "Carrier Shells".
[Ponder, 1983, p 2]

Onustus

Swainson, 1840
Onustus indicus

Xenophora

Fischer von Waldheim, 1807
Xenophora peroniana