Abstract: A medical device for entraining biological stones during medical procedures for the fragmentation of urinary, biliary, pancreatic, and other biological calculi and safely removing them from the body. The device includes a guidewire having a longitudinally-extending wire core. A portion of the wire core more adjacent the distal end thereof than the proximal end thereof is wound to form a helical coil which tapers in diameter from a larger diameter end at the proximal end thereof to a smaller diameter end at the distal end thereof. At least a portion of the core forming said helical coil is made of a super-elastic deformable material which collapses upon retraction into a tubular sheath and which reforms into a coil upon deployment from the sheath.