It looks like this egg has a little cloud hanging around it and my gosh, look at that adorable hat. It's actually recommended that you do not remove the hat as the creature inside will become angry and refuse to hatch. But don't worry. While the accumulation of a cloud around the egg might worry you, it's actually necessary for the creature inside to grow. Without it hanging around, instead of a colorful egg you would just have a dull and colorless egg and creature.
The Stobow is an adorable creature that loves all things rainbows, green, and hats! But despite the fact that these little critters look completely harmless, you would be wrong. During the month of March is when they are most active, and they have a lot of hobbies that might be considered somewhat rude. They enjoy stealing your money and using it to, well, no one really knows. Just that it is gone and the Stobow is usually to blame. Some say that they hide everything in their hat, but that hat is only so big! Perhaps it's a magical portal thing. They also typically enjoy playing pranks on passing neighbors and young children by running out and scaring them.
The Stobow typically enjoyed higher areas, meaning they like the mountains where they can be closer to the sky. Besides they have a literal rainbow always following them, so they enjoy being out in the sun so everyone can see their colors. So if you see a rainbow flying at your feet, take care to see if it is a Stobow first. Otherwise perhaps you found their pot of gold!