What is the white material falling from the sky in Skeleton Dome

When I first when into the level I thought it was Snow but when Shara said that it wasnt snow I tought some and came up with 2 ideas : 1. The Material was soot 2. The Material was the 'dead' desires that never came true for people (backed up by the fact that the White World Ring found there Sonic say that it holds 'desires'