What is similar to a tuba?

A euphonium is similar to a tuba, as both are brass instruments that belong to the same family and share a similar sound quality. They both have a conical shape and utilize valves to change pitch, although the euphonium is typically smaller and has a more mellow tone. Additionally, the sousaphone, often used in Marching Bands, is another instrument akin to the tuba, designed for portability while maintaining the tuba's distinctive sound.