Arduino Ethernet Shield on Arduino Mega Pin Usage! I currently have an Arduino Ethernet Shield which is Mega Compatible. I've found on the Arduino Ethernet Library https://www.arduino.cc/en/Reference/Ethernet that the Shield uses different Pins on the Arduino Uno and Arduino Mega. How is this possible? The Ethernet shield isn't connected to those pins mentioned. 

Arduino Uno:
Pin: 13 - SCK
Pin: 12 - MISO
Pin: 11 - MOSI
Pin: 10 - SS for Ethernet Controller

Pin: 4 - SS for SD Card

Arduino Mega:
Pin: 52 - SCK
Pin: 50 - MISO
Pin: 51 - MOSI
Pin: 53 - SS for Ethernet Controller

Pin: 4 - SS for SD Card
Those 4 pins D50 to D53 are the ICSP pins which appear twice on the MEGA; the Ethernet Shield uses the second set of connections located in the middle of the Mega board.

The header files gets told (by the Arduino IDE) that the board is a MEGA so the compiler uses those pin numbers to connect.