Plant it to grow Puzzle Brick. This brick is just made out of puzzlingly shaped pieces. It's not much of a puzzle itself. Just a brick.
Puzzle Brick Seed price in Growtopia: sells for about 1/WL, buyers pay about 1/WL (median of 16 offers from community Discords, past 30 days). Live price chart and the latest buy and sell offers.
Recently sold at: HOSPITALBEDSTOCK, ARROW, JOOJZ, MILSA, QLPKU