We studied red snow in Alaska to learn why these blooms vary in their microscopic life. By examining snow using microscopes and genetic analysis, we found that the ground beneath, either glacier ice or soil, dictates which algae grow. Algae on ice were mostly round, while those on soil were larger and had diverse shapes. Factors like snow depth mattered more than nutrients. This proves the underlying surface acts as a reservoir for life, shaping how red snow develops.