Elder Tree Seed is a gadget from Doraemon: Story of Seasons.
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Elder Tree Seed is a gadget designed to return the polluted and dying environment back to its original pure state as in the past, making it in a way a gigantic Time Machine. Once planted, the Elder Tree Seed will mature and grow to its full state in a short span of time and begin the swapping process, limiting to only land, water, and air, until the location's environment is deemed desirable.
However, because the gadget itself is only a prototype it was never released to the public. In addition, a dreadful side effect is that it can create a Gigastorm capable of sucking anything, including living plants and creatures, into a Time Vortex and sending them any times and places between the distant past and the faraway future. In order to reset and destroy the tree, a specific golden leaf must be removed from it.