Most animals have a pecking order. I don't think humans are that far above that.
What we now call bullying is a part of growing up. I also had a bully situation. I survived it and so did you and so will your daughter.
Don't get me wrong I know the anger that comes from a parent when our child feels hurt.
We can never control what other people do and say, so I feel society has made a huge mistake teaching kids to be upset if they are bullied, it just ads to it.
Personally, I would tell my child to answer Mico. Yeah, Mico, this is what I am eating for lunch so what? Or every time he made a comment just say.. I don't care... Teaching children that something bad is happening to them and teaching them to appeal to authority each time also has it's limits.
At home make sure you stay in touch with her feelings, report the incident, but I also recommend teaching your daughter to brush it off will also be helpful.
Again, I am not minimizing her feelings or yours, I am just saying there will always be mean kids. Parents in my opinion should teach their kids to become bully proof as much as possible. No one else can solve it.
Edited to add, I worked in a school as an SLP Assistant as I was finishing my education and I would recommend teaching her to look right in Mico's eyes and say So what or Where did you learn that? I would practice it with her over and over until she feels comfortable doing it. No girl should allow herself to be bullied.