Paleontologists examining slabs of limestone from the world-famous Jurassic Solnhofen lithographic limestones of Germany (which also produce Archaeopteryx, of course) ran across an 8.5 meter-long (almost 28 feet) drag mark left by an ammonite--with the very cephalopod that created it preserved in place at the end of the trail. It's technically called a tool mark, because it was created postmortem--not by a living organism.
With apologies to the Rolling Stones ("Mother's Little Helper"), a description of the occurrence could probably be summed up in this sentence: What a drag it is rolling old.
Because here's what happened. You get a dead ammonite drifting along near the sea bottom. It's still semi-buoyant, and part of its shell grazes the bottom as it gets dragged along by currents. Finally, the shell drops out of suspension and hits the ocean floor, coming to rest at the end of its lengthy drag mark.
This is the longest drag mark yet discovered where the actual animal that created it is also found.
See the complete technical article over at An 8.5 m long ammonite drag mark from the Upper Jurassic Solnhofen Lithographic Limestones, Germany.