Melocactus azureus Cactus Matucana madisoniorum Also known as

Matucana madisoniorum Also known as Submatucana

Care is more similar to a succulent too

Parodia concinna  Also known as Notocactus

Mature plants are roughly 1' diameter

They are probably E

Melocactus azureus Cactus Matucana madisoniorum Also known asMelocactus azureus Family: Cactaceae. This is a nice cephallium forming cactus with blue to blue green skin. It looks and grows like a normal cactus for several years but once it gets big enough the main plant stops growing but produces a large hairy inflorescence that continues to grow for the rest of the life of the plant. Eventually the inflorescence can be taller than the plant itself. This is more tropical than most cacti so it doesn't like cold