The cave spider, s, is a monster that appears in NetHack. They are capable of hiding under items, taking some players by surprise. Cave spider corpses have a 7% chance of granting the poison resistance intrinsic.
Cave spiders are often generated in groups. As a grounded hiding monster, cave spiders generated via level creation will always be given a random item to hide under.
While not particularly dangerous for the first hiding monsters you are likely to encounter, cave spiders have a somewhat low AC that can make it slightly difficult to hit them. Throwing an item at them will cause them to hide under it most of the time; this is useful for keeping them at bay and picking them off, or even escaping if the situation warrants it.
This can also be put to use in some treasure zoos, where a hiding cave spider can block the door and hem in the other monsters; you can then attack them from range at your leisure, e.g. with a polearm or lance.
- See the encyclopedia entry for spider.