bayonet fitting for lenses?

I have an ike housing with 67mm thread and i have seen on the net that you can get a adaptor with a bayonet fitting on it, which was a 67mm thread on the other end,to attach to ike port,and also lenses (eg: macro--wide angle ) that have bayonet fittings i think they are from inon i maybe wrong ,anyone seen these and if so where can they be purchased , in australia if possible but not all important ,as they would be much easier to change underwater then the thread type ,as i can just leave the adaptor attached to the port and change lenses much faster and easier,any help would be great.