Sand Bird
Sand Bird is a legendary bird that Mario helps to hatch in Super Mario Sunshine. Plungeloes were walking on the mirrors near the egg's protective tower. The egg's tower has a device at the top that gathers sunlight and directs it at the egg. So with the Plungeloes on the mirrors light couldn't warm the Sand Bird's egg. Fortunately Mario defeated them and the Wiggler sleeping on the device.
After hatching it the mini-stage could be accessed where Mario rides the Sand Bird around a tower to collect eight Red Coins. The bird itself seems to have been made of sand blocks and it has no eyes. It can flap its wings and screech but not much else is known about this creature.
There is a small easter egg about the tower the sand bird flies around. There is a single tower that you can walk on and there are surrounding towers. This resembles the Tower of the Wing Cap from Super Mario 64.