Thallium is a greyish metal that isn’t usually found free in nature. It has to refine from other metals. It’s highly toxic and was used in rat and insect poisons but has since been banned. It’s still used as a poison by those with nefarious intent. It is now used in some sorts of x-ray imagery in tiny quantities.
Deathwatch beetles will tap and scrape at the inside of old decaying woods, it is their primary food-source. Some say that they were the inspiration for Edgar Allen Poe’s Tell tale heart. They will eat most slightly rotting wood and wood related fugues, and possibly occasionally found their way into untreated or rotting wood floors and even poorly made caskets and scared the “heart” out of more than a few people.
Lead is a heavy, malleable and slightly toxic metal. Its uses have been varied throughout time, including use in currency, armour, weapons, as an alloy and even in primitive medical uses until its toxicity was well known. It is still used in medicine, but almost always as a shield against radiation in x-rays. It also gets used in manufacturing.
American cockroaches are different to European and even what most Australian’s would call cockroaches (generally in Australia its a field cricket). They are exceptionally hardy insects and are generally able to survive fire, floods, and even partial decapitation. This isn’t true of all species of cockroach, so its not recommended you should try it. It is also said they are the only thing that is likely to survive a nuclear winter, should nuclear apocalypse come.