The 13th century Hindu philosopher Arulnandi Shivacharya wrote a work called the Shiva Jnana Siddhiyar, which among other things contains a refutation of Buddhist philosophy. In this excerpt, various Buddhist theories of what the ultimate cause of the body is are refuted:
If you say bodies are formed from the mixture of four elements, then these cannot unite as their natures are opposed to each other. If you say they are formed by the union of blood and semen, then account for toads being found in the heart of rocks, and worms in the heart of trees. If you say the real cause is good and bad Karma, then these, being opposed, cannot join and form bodies. If food is the cause, then the food which in youth develops the body is not capable of preventing decay in old age. If intelligence is the cause, then that which is formless Chaitanya cannot assume Achaitanya (non-intelligent) form. If you assert that bodies are formed from nothing, then we could cull flowers from the sky.
My question is about the part in bold, which is arguing that intercourse cannot be the ultimate cause of the body, because there are toads which are found in the center of solid rock, and they couldn't have been produced by intercourse since there's no way that toads could have gone inside a solid rock and reproduced.
This statement struck me as rather odd, but then I found out from the Wikipedia article Entombed animal that claims of toads being found in solid rock are surprisingly common across many cultures:
Entombed animals are animals reportedly found alive after being encased in solid rock, or coal or wood, for an indeterminate amount of time. The accounts usually involve frogs or toads. The reputed phenomenon, sometimes called "toad in the hole", has been dismissed by mainstream science, but has remained a topic of interest to Fortean researchers.... References to entombed animals have appeared in the writings of William of Newburgh, J. G. Wood, Ambroise Paré, Robert Plot, André Marie Constant Duméril, John Wesley, and others. Even Charles Dickens mentioned the phenomenon in his journal All the Year Round. According to the Fortean Times, about 210 entombed animal cases have been described in Europe, North America, Africa, Australia, and New Zealand since the fifteenth century.
Conspicuously absent from that list of places is Asia. So my question is, are there any references in ancient India to entombed animals? The work I quoted above was written in the 13th century. But I'm wondering whether there are earlier references to this phenomenon. Arulnandi Shivachrya refers to this phenomenon as if it's common knowledge, so I'm guessing older sources would mention it as well.