You need to collect 300 blobules without dying. This sounds tricky but it is actually quite easy. Level 2-12 is great to earn this achievement on. The level has nearly 200 blobules that can be collected in less than 1 minute and it is essentially impossible to die. From the start of the level, just fall down into the area with all the blobules and springs. Collect as many as you want. 150 is probably good. Then pause the game and restart the level. Collect as many more blobules as it takes to unlock this achievement, which will depend on how many you got on your first go.