The Ice Stone is a figure slightly smaller than Sonic the Hedgehog's full height. It has a grey square rock stand with an almost ellipsoid blue crystal fixed vertically on a light blue ring on top of it. Inside the blue crystal is a snowflake symbol which slowly rotates on itself horizontally.
In Sonic Adventure, and its enhanced port Sonic Adventure DX: Director's Cut, the Ice Stone appears in Sonic, Tails and Big's storyline. In Sonic and Tails' storyline, the Ice Stone can be found at the end of alleyway behind the cinema near the casino in Station Square, after the player has cleared Casinopolis. In Big's storyline, however, it can be found behind the Twinkle Park lift in the Station Square Adventure Field, after the player has cleared Twinkle Park.
The Ice Stone is to be taken by the player to the tunnel that leads to the Mystic Ruins Angel Island Adventure Field. When passing through the tunnel to the island, the player will arrive at a cave surrounded by ice. There, the Ice Stone must be placed on a pedestal with a square blue crystal in order to open the path to Icecap.