In Another Crab's Treasure, you level up by collecting Microplastics from fallen enemies. While you don't need to grind Microplastics to progress through the game, there is a method you can use if you want a few extra levels.
Another Crab Treasure | 100,000 Microplastics in 5 Minutes | Microplastic Farm Guide
This is the best place to grow microplastics in Another Crab's Treasure.
The best place to farm microplastics in Another Crab's Treasure at the start of the game is the very first area you visit: Cave of Respite.
Remember when you first started playing and you had to run away from all those crabs because you didn't even have a weapon? Yeah, that's the best zone to farm Microplastics in the beginning.