What do io of jupiter and triton of neptune have in common?

Both Io nad Triton are moons that orbit around planets. Io is the fifth moon out from Jupiter, while Triton is the largest natural satellite of the planet Neptune.It is similar in size to Earth’s moon and was discovered in 1846 .
The similarities between Io and Triton lays in the active volcanic like activities.

Ascenario that doesnt  include any modern objects like electricity

Icant awnser the qustion bc u have the planets not listed