I've run through the "What's your box topic" and I don't think this has been mentioned before. My bento box had just arrived yesterday and I'd like to know if it's microwavable. It's bottom says that it's made of some synthetic plactic (which I don't know how to spell) and is able to withstand temperatures from -20 to 120'C. Would I be able to put it in the microwave (lids removed)? And also, for how many minutes?