The Raspberry Squid is an RGB LED with built-in resistors and header lead sockets that can fit directly onto GPIO pins of a Raspberry Pi!
There are three connections (red, green and blue leads) that control the red, green and blue channels of the LED’s colour respectively. The fourth (black) lead
should be connected to GND on the Raspberry Pi.
It's a convenient way to quickly learn how to code RGB LEDs without having to use breadboards or resistors. Wiring and code examples can be found here.