system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How is animal A closely related to animal B, but looks/acts NOTHING like animal B?

I learned that the rock hyrax is the closest relative to an elephant... they *literally* look nothing alike!! Also, the king cobra is not a cobra, even though it looks identical to one, but instead in its own genus. Another example would be the extinct genus *Indohyus* is closely related to the whale, but (using Wikipedia reference) looks like a mouse-deer.

Why is that?
gpt
The word close is... Relative. It is often better to compare skeletons and organs than exterior appearance, since exterior appearance can change relatively quickly on an evolutionary timescale, while skeletons take a very long time to create new joints/fuse joints and new organs and chemical processes develop very slowly. || There is also something called convergent evolution, where creatures from very different lineages end up with similar traits - this happens because certain traits are very useful and are often stumbled across by completely separate evolutionary paths. This all means that some creatures can look very similar to creatures that are only distantly related to them, while other creatures can look very different from close relatives.