Why is selling of Balot done at night?

Balot is one of the Filipino especial dishes. It is one of the most requested dishes of men who are in drinking session. They said it's delicious and rich of protein. At first, I didn't understand why it has to be sold during night. Never in my life did I see any Balot vendor during day time. This thing made me wonder why. Why in a world this kind of food has to be sold at night? I thought it is illegal but it's not. My big brother told me that Balot is an egg. He explained to me why it has to be eaten with the absence of the light. I was amazed and curious. I wanted to see it with my two eyes, So my brother bought one. It's true, an egg with undeveloped chick! That is the reason that vendors have to sell it at night because Balot has to be eaten when the light is off. Though they said it's delicious, yet never did I try to taste it.