Despite not being made of metal, turtle eggs and sniffer egg blocks both use the "Metal" sound group for their sounds.

While this sounds fine in vanilla, resource pack creators that want to redefine the metal sound group run into an issue wherein these blocks also get redefined, which causes an odd dissonance in behavior versus sounds.

Below is an example of a resource pack that applies the netherite sound group to the metal sound group, and only the metal sound group.
example.mp4