However, I find the term "dark SQUID" to be fairly evocative, so have a picture I drew of one on my phone:
The phone itself utilizes Wacom tablet technology (used in various fashions by many, many digital artists) to get a lot of feedback from the stylus, allowing you to do things like vary the intensity of a stroke by changing how firmly you press down with the stylus. It also allows you to hover over things (to get tool-tips for instance) like you can using your mouse on a computer, because it can actually sense the stylus tip over a centimeter away from the phone surface. The stylus is also great for any sort of fine work on the screen, like typing.
While looking up Wacom Co. I learned that their tablets actually power the accompanying styluses [styli?] using the fascinating technique of resonant inductive coupling using magnetic fields, meaning the phone is actually wirelessly powering the stylus while it's in use. Maybe that's why it goes through battery faster...
(Finally, while looking up "squid" in the dictionary to see what the correct plural is, I discovered that though the word is attested to all the way back to around 1605-1615, the origin is uncertain. Interesting.)