Speaking of a grain of salt, did you see that post yesterday of the ultra-micro RFID chips for use by intelligence agencies?  https://thefutureofthings.com/wp-content/uploads/2007/10/hitachi-smallest-rfid2.jpg Here it is on a finger: https://o.aolcdn.com/images/dims?thumbnail=1200%2C630&quality=80&image_uri=https%3A%2F%2Fwww.blogcdn.com%2Fwww.engadget.com%2Fmedia%2F2007%2F02%2Fhitachi-rfid-powder.jpg&client=amp-blogside-v2&signature=5c7b722a16f78aff248815e68e51c4e36fe0bd92