Pokemon GO trainers aren't sure what to make of the blue eggs popping up in-game.
Pokemon GO has a series of in-game markers for different events. From Raid difficulty to important areas and simply celebration special effects, there seems to be no shortage of unique and useful mechanics trainers have seen utilized to tell different aspects of the game apart. One of these are the eggs that appear above each Gym when a Raid is announced. They often appear once the Raid is announced and come in a variety of colors to denote difficulty.
Here's what the blue ones mean.
What do Blue Egg Raids mean in Pokemon GO?
Blue eggs mark a four-star Raid in Pokemon GO. It's unsurprising some players may be confused by their presence as they tend to be fairly rare — almost entirely reserved for events.
One-star Raids have pink or red eggs. Three-star Raids feature yellow eggs. Finally, five-star Raids have deep purple or navy eggs with white stripes.
Once the Raid timer is up, the eggs will "hatch" in a puff of smoke to reveal the Pokemon headlining the Raid in that area.
Trainers can check out the Raids in their area by tapping the Nearby button on the bottom right of the screen while looking at the overland neighborhood map. Each Raid is noted by a different bubble explaining the time remaining or time when the Raid will start, its difficulty number, and the Pokemon currently available as part of the Raid — either in full color or silhouette form if still unregistered in the Trainer's PokeDex.