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retains the coordinates of the last time it was placed
with an eye of ender can be made into the Ender Myosotis

one-use teleport with the condition that you are in the same dimension as the saved coordinates

while in inventory, completing certain tasks may transform this and give you some benefits

obtained by drowning in a swamp biome with a Primal Pearl in inventory
benefits on right-click you can put a special Plant Essence block with the pearl indefinitely (useful for scaffolding)

obtained by breeding 20 animals with a Primal Pearl in inventory
benefits while in hotbar, you deal extra damage to undead mobs (equal to Smite IV)
disabled if you kill a Villager or an animal

obtained by killing 13 villagers with a Primal Pearl in inventory
benefits while in main hand, undead creatures can't damage you (still take knockback)
disabled if you cure a Zombie Villager

obtained by killing 25 Drowned with a Primal Pearl in inventory
benefits while in main hand, gain Water Breathing
disabled if you kill any fish/water friendly creature

using it on Bedrock teleports you to The End
breaking a Beacon with it drops instead a Heart of Glass

In a 9x9x9 area of effect every player receives Regeneration II. Glows and can be waterlogged.
The potion effect can be changed by using a Lingering Potion of the desired effect on it.