O button (blood type)

An emoji representing blood type O, designed as a button with the letter O inside a red square. This symbol is commonly seen in medical facilities.

Type O is one of the most common blood types worldwide. It is considered particularly important in emergency situations and is often referred to as the 'universal donor'.

Medically, type O blood has special value as it can be transfused to all blood types. Due to this characteristic, it is highly valued in medical systems worldwide and is particularly in demand during medical emergencies.

In the digital age, this emoji is also used to symbolize perfection or balance. Like its circular shape, it can represent 'completeness', and in games, it's often used to mark targets or precise locations.