Good afternoon internet hive mind. A friend has inherited a bike that has a wobbly bit somewhere inside the bottom bracket. I'm taking bits from old bikes to cannibalise into a new one to make it rideable and to be honest the whole thing is a great learning experience for me anyway, but I've hit a problem. In the past I've removed the bottom bracket with the correct tools, then to remove the bit that contains the ball bearings I just use an adjustable wrench to unscrew it. On this bike it isn't nice and hexagonal shaped to allow a wrench to grip properly, it keeps sliding off. It looks like some kind of unique tool is needed, can anyone assist me in removing this so I can replace the bottom bracket? I've attached a picture of the offending bit.