Mum-mums have the same behavior as Limbos. If a Mum-mum notices Banjo and Kazooie, it starts chasing after them. The duo can use most attacks to temporarily knock down a Mum-mum. Banjo and Kazooie can only defeat a Mum-mum entirely by using the Wonderwing move.
Inside of the pyramids, a Mum-mum guarding King Sandybutt's Tomb can be found. As soon as Banjo and Kazooie enter the place, it warns them to leave. By continuing onward, Banjo and Kazooie have only 59 seconds to find their way through a maze, while avoiding the Mum-mum, and reach King Sandybutt's chamber on the other side. When Banjo and Kazooie reach the chamber, it unhappily says that they reached King Sandybutt's "golden relic."