The Reflecting Pools are essentially columns of water shooting into the air, from within one can see images. However, the Reflecting Pools' water is not normal, as evidence by the light that it emits.
Features and traits
Reflecting Pools allow users to view people and locations from great distances, and can replay past events that they have observed. On the Floating Island, their abilities make them suitable for getting security footage. However, the only locations viewed were those on the Floating Island, which may be the limit of their distance.
The Sonic Underground first encountered a Reflecting Pool on the Floating Island, where the image reflected on the column of water was their mother, Queen Aleena Hedgehog. However, their excitement at seeing this was short-when Knuckles the Echidna jumped out of the pool and attacked them. Hearing Sonic's warnings about the thieves Sleet and Dingo, Knuckles used a Reflecting Pool to view their actions, through which he saw them steal the island's Chaos Emerald.