This is bait for fishing. Equip a fishing rod and then use this bait on water that you are standing next to in order to start fishing. This bait won't catch anything but the Catch of the Day, which changes each day. Fish have a chance to escape, though! Bonus: Fish caught this way can be larger than the normal maximum size!
Catch-of-the-Day Bait price in Growtopia: sells for about 70 WL (median of 3 offers from community Discords, past 30 days). Live price chart and the latest buy and sell offers.
Recently sold at: OKDP, UP26, GACHASHOP101, F0AG