Some organisms that share a common ancestor have features that have different functions, but similar structures. These are know as

Vestigial structure
Analogous structures
homologous structures
Fsosill structures

homologous structures

The correct answer is homologous structures. Homologous structures are features in different organisms that have similar underlying structures, indicating they share a common ancestor. These structures may have different functions in different organisms, but their similar features suggest a common ancestry.