A Lumalee serves as a "shop," where Mario (or Luigi) can purchase either a Life Mushroom or a 1-Up Mushroom for 30 Star Bits. Lumalees can be found in several galaxies and tend to appear before boss battles. Once Mario has made his choice of purchase, a Lumalee is fed the right number of Star Bits automatically and proceeds to transform into the mushroom of his choosing for him to collect. Because of this transformation, Mario can buy only one item from a Lumalee per appearance in that playthrough of the stage.
In Super Mario Galaxy 2, Lumalees serve the same purpose as in the first game. In addition, by doing certain missions, two Lumalees holding sticks with Chance Cubes on the end will appear in a pipe that is on the left ear of Starship Mario. The first Lumalee will turn into a Chance Cube for 30 Star Bits. The second Lumalee will turn into five Chance Cubes for 100 coins. The possible outcomes from both Luma Shops' Chance Cubes are a single Star Bit, a 1-Up Mushroom, three 1-Up Mushrooms, and five 1-Up Mushrooms.