Ty hamsterIt's called a Shimano XTR tool. Park do them; it also fits Middleburn crank lockrings.
Lol thanks very much appreciatedYes, that should fit. Use some big washers and an M8 bolt to hold the tool onto the bottom bracket for the crucial loosening - saves skinned knuckles! Apologies if I am teaching you to suck eggs, but remember that the RHS bottom bracket side has a left hand thread.