Pellets on Slither.io
Pellets are the food that snakes must eat to grow bigger and increase their length. The bigger the pellet, the more it will contribute to a snake's growth. Pellets spawn at random on the ground, but they are also generated by players who use their movement burst. They on average gives you 1-4 mass per regular pellet. Larger pellets will only be generated when a snake dies. These pellets will spawn in clusters of around the same size the snake's body segments had when it died, the remains of a dead snake consists of larger pellets with a mass of around 10-40 each. However the amount of mass depends on the size of the snake before it dies, the pellets left behind represents 20-25% of the mass it had only. There are also special pellets that appear larger than most other pellets and move around the screen, generally trying to avoid the player; I call it "butterfly pellet." When eaten, these special pellets give a much larger amount of length to the player and so it can be worth it to use your speed ability to grab them, especially early on in a game. On average, a butterfly pellet caught and eaten by speed boosting will grant you up to 50-60 mass.
Say that there is a heavily populated area. When a gigantic snake, possibly on the Leaderboard dies, lots of other snakes (big and small) rush in to grab some of the mass. Greedy snakes start killing others speeding in the huge amount of mass and eat their mass, while other snakes bump into each other, causing more mass than what was, to begin with. More snakes start rushing in and start running into each other by accident, along with some greedy snakes. In the end, there are tens of thousands of mass at that area which only a few surviving snakes will be able to pick up. It can be rewarding but deadly if not executed properly. It's best to avoid Mass Rushes unless you have good skills/experience or you are just starting off with less than 500 mass. Mass rushes won't happen in an unpopulated area, such as around the edges, but a snake may be in the vicinity and surprise you, ending up killing you. Set your slither.io to "Low Quality" if you are experiencing lag. Lag kills especially in Mass Rushes in Slither.io.