A
dunnasae (pronounced "dunna-
say) is an original creature developed for the
Advanced Dungeons and Dragons role playing game. Yep, it is
copyrighted to
Warped Reality Studios, so don't go stealing it, unless you're a very high level
thief :)
The dunnasae live in damp caverns at least one mile underground. At first glance, they appear to be thick oil slicks on the walls. They eat silicon, and that's what they're doing on the wall. They can be peeled off and saved in glass containers for up to one week, wherein they digest their way out of the bottle.
They are rather innocuous creatures, about a foot in diameter. They do not talk as far as anyone can tell. They move very slowly, and do not fight back if attacked, although they will do their best to eat any metallic weapons used against them. Fire kills them rather quickly.
So, what good are stupid oily sheets that cling to walls, you may ask? They do have one interesting property - they live in multiple dimensions. If one comes in contact with a human, it will merge with their tissue. They can swim rather quickly to any portion of the human. It will tend to sink to the soles of the feet, wherein it will feast on the dirt and sand the human walks on.
As I mentioned - it is a multidimenstional beast, and as such it can act as a living portable hole, storing any non-organic material up to five cubic meters. As long as the host allows the creature to eat (and having a small pouch of sand comes in real handy), it will respond to human thought and swim to any portion of the body when directed. The beast can make any stored item appear from anywhere the host wishes, like a sword "magically" erupting from one's hand or a metal quarterstaff bursting from one's colon, wherever the user wants.
As with all things, there must be a risk involved for having such a useful creature. The first one is in order to remove the dunnasae, you must will it to a part of your body and then proceed to burn that body part off. The second is that you must never put organic material into the dunnasae, as it will learn that you are organic and tend to try and absorb you, which will drive it crazy and force your body parts to attack things around it. Organic extends to rope, leather, rations, etc. Wooden scabbards or sword hilts are also not allowed.
Dunnasaes are very rare, and hence very expensive should one be found. Make sure your RPG player fully understands the drawbacks of having one live inside your body, and be merciless should they forget.