Osteons are the basic organizational units of

Osteocyte = bone cell

(Haversian system)

the basic structural unit of compact bone; consists of central canal, lamellae (rings), lacunae, osteocytes and canaliculi

The osteon or haversian system / həˈvɜːr.ʒən / (named for Clopton Havers) is the fundamental functional unit of much compact bone. Osteons are roughly cylindrical structures that are typically several millimeters long and around 0.2mm in diameter.