Metaphoric rocks are not 'like' anything else. Their transmutability makes this rock type very hard to identify. These elusive 'performers' are often found being anything but rocks. They can resemble potatoes or take on musical properties or sometimes turn to candy or even imitate bard chickens. They can become the size of Volkswagens or as small as diamonds.
Believe it or not some highly successful individuals may even be identified as part of this 'metaphoric' group. Just because someone has certain 'cool' properties however, does not necessarily put them in this particular category of 'rock'. Nor should these rocks' undersides always be confused with bargain sales, their disposition with hard hearts or uncomfortable beds and/or just about anything you might be tempted to compare them to.
As the name suggests metaphoric rocks are always in a state of constant transition. Though multi-faceted and ever changing in form, they do process one or two recognizable properties that make them very attractive. Most metaphoric rocks, for instance, have a kind of waxy poetic feel to them, figuratively speaking. The rocks appeal to all five senses, but if you're looking for a literal sense, you'll never find it. Their chemical structure is highly irregular. It is of a more descriptive composition than can be identified here.
The best test for a metamorphic rock is to put it in a room of objects and measure how long it takes for it to compare itself. The longer it takes, the less metaphoric its makeup.
In fact, as far pervasiveness, this rock type 'makes up' the majority of rock-'like' substances on earth!
But then again, by definition, you will have looked forever and never metamorphic that is 'like' anything.