You pretty much know what your pet clam or oyster will do in any situation: nothing. But cats not only do the unexpected. They also like to create the situation.
P.S.–Please, please don’t let your cats mess around with frogs. Most frogs and toads have chemicals in their skin that can make a mammal painfully and expensively sick if it gets into mouth or eyes. And it’s not a frog’s idea of fun.