Yep, mojano. If the rock can be removed easily, take it out and torch the nem with a lighter, etc. Scrape the remenants off with a blade and put the rock back. Note that the nem will suck back into its hole if you spook it, making it harder to get to. Otherwise there are products (Aiptasia X, Joes Juice) that you can use to smother and chemically burn it. Aiptasia X and Joes Juice are just premixed kalkwasser pastes so you can also by a jar of kalwasser and mix the powder with RO/DI water to make your own (the thicker the better and the longer you leave it the better). You apply the paste with a syringe type device without the needle.