SpongeBob SquarePants: Battle for Bikini Bottom - Rehydrated

When you approach the boss, you'll have to defeat it. Once so, you'll get the jelly and the "Jellyfish Jam" achievement/trophy. After giving the jelly to Squidward, you'll get another spatula and the "Jellyfishing" achievement/trophy.

Note to self: Jellyfishing is based on an episode where Spongebob and Patrick takes Squidward to jellyfish, and Jellyfish Jam is also based on a episode where Spongebob brings home a jellyfish which later causes chaos.

To earn this achievement, you'll need to complete the main mission of the first level, Jellyfish Fields. This involves progressing through the whole level, and defeating the boss at the end, the Jellyfish King. Progress through the level normally and after defeating the boss, you'll be presented with a slide to ride down. Avoid the explosive tikis on your way and at the bottom you'll find Larry the Lobster. Talk to him and then you'll find a flower behind him that will bounce you back to the start of the level.

Bounce off the flower and after a loading screen you should automatically spawn into the level already talking to Squidward. He'll trade you the jelly that you got from defeating the boss for a golden spatula. Take it, and the achievement will pop.