I'm Black On The Outside, But Blue On The Top. On The Inside

Riddle: I'm black on the outside, but blue on the top. On the inside I'm usually green, but also reddish, purplish. I can be sweet and sour. What am I?

Answer: A blueberry.

Source: https://www.riddles.com/3621

I'm black on the outside, but blue on the top. On the inside I'm usually green, but also reddish, purplish. I can be sweet and sour. What am I? — I'm black on the outside, but blue on the top. On the inside by Gia Minh Bui v1.

Riddle: I'm black on the outside, but blue on the top. On the inside I'm usually green, but also reddish, purplish. I can be sweet and sour. What am I? Answer: A blueberry. — by Gia Minh Bui v2.