Vitality,
referred to as Hearts, is the main in-game currency of Abyssrium. It is produced by the Lonely Corallite when tapping the screen, or by tapping friends when they notify you. Coral will produce Vitality even when the game or device is closed. Another method of obtaining Vitality is to complete the various quests the game gives you.
Source(s)
Vitality can be obtained by tapping the screen, coral, and tapping friends when a heart appears above them.
Trivia
- According to the game itself, Vitality can also be refered as Hearts.