Adamant Algae

Overview
Rare algae that grows in water gathered around adamantine. A typical pool contains 32 ounces of dark red liquid, which becomes useless 30 minutes after removal from the pool unless stored in an adamantine vial (200 gp), which makes it last for 1 month.

Location
Oceans

Uses
Its dark red liquid that doubles natural healing rate for 24 hours (requires 1 ounce per 100 lb of body weight) meaning that hit points regained from expended hit dice during a short rest are doubled and the amount of hit dice recovered during a long rest is doubled.