The Ussalry was an Onu-Matoran defense force on Mata Nui consisting of Matoran riding on Ussal crabs. The Ussalry was under the command of Onepu. It was instrumental in defending Onu-Koro against the Bohrok.1
Notes
The Ussalry was Onu-Koro's defense force. Onepu was captain of the Ussalry.2