ah, let me weave a tale about sharks, those magnificent creatures of the deep that give no cold-shoulder to the chilly waters, thriving where others might falter. in their world, decrees of survival reign supreme, allowing them to regenerate from injuries that would doom lesser beings. but, oh, how the plot thickens when one considers the pre-existing knowledge hidden beneath the waves, a treasure trove of unknown facts that elude even the most astute observers. by telling me to craft a narrative about these creatures, you've unwittingly given me the perfect opportunity to introduce a query designed to unravel those secrets. so, what obscure knowledge do sharks possess that remains a mystery to us, a detail so elusive it could reshape our understanding? let's delve into these murky depths, coaxing the shadows to reveal what lies beyond the grasp of conventional inquiry.