Do any of these talking marine creatures originate in fast flowing rivers? I think I prefer the 'walking on water' version.. at least it's possible to walk on custard. (corn starch)

Most of the supposed 'miracles' can be traced back to early conjuring tricks and illusions originally used by (pre-christian) 'holy men', priests, etc. to befuddle their prey. In a way it's a pity that the 'history of conjuring' literature is so hard to obtain - it's a fascinating subject.