I've usually found Morrisons to be very good for meat, probably the best quality of all the supermarkets. However, recently bought beef shin from there for a casserole and it was full of tubes, very offputting obviously (we didn't realise until we were eating it). Does anyone know what these tubes are called? - is it a type of artery. And is there any way to avoid these tubes in future? I know braising steak is an option but not always available.