A group of seven musicians - or indeed, any group of seven things - is a septet.
Halogens
A Chinese 7-piece puzzle is a tangram.
heptad
The general name given to the elements of Group IA (1) is alkali metals.
A Chinese 7-piece puzzle is a tangram.
A Chinese 7-piece puzzle is a tangram.
Petrified wood
Tangram
antifederalists
A group of kangaroos is called a mob.
Brigade
A wolfpack