"as a joke" There's no need to project motive onto such a premise. One needs only to question the possibility of movement. Religious rituals are just as likel

"as a joke" There's no need to project motive onto such a premise. One needs only to question the possibility of movement. Religious rituals are just as likely, as well as being deposited with ani al droppings after becoming an unfortunate snack for some scavenger or carnivore. Also flood runoff, why not?