Hi guys i fell a bit confused. I just found a Mysterous egg?

in the forest where is the structure to hunt.
What hare this Mysterious egg? The MC say i can perhaps find more. But what are they for?
Edit# now i have 12 egg. And i see that i can use this Mysterious egg on a statue in the forest. But nothing happen.
Someone know how many egg i need? And why i start to find this game only now?
Edit#2
Ok, i do not know how many ppl know about this. Because i search and i see that some ppl write about this egg. This happen on in april in game or april in real world. Is an event as i understand. Every 21 egg, this statue in the forest, give you a Fairies equipment.
With 105 egg the statue give me:
Armor = Fairies Helmet, Fairies Armor, Fairies gloves, Fairies boots. Every piece are much stronger then the leather armor set. Give bonus on a lot of status.
Weapon = Fairies Bow (attack 23, agility 2, Luky 1,) surelly better then the normal boy attack 3

If you save before give the egg, you can obtein every piece with 2 slots!
After the 105 egg if you find other 21 eggs, the statue give only 5 coin puch. I think there is no more equipment
I just do not understand why this info is not in the walkthrough.
Sad that there is no ring or sword o dagger