Lottia. gigantea is a keystone species in the rocky intertidal zone (Paine, 1994). Better understanding of L.gigantea will provide further insight to the community ecology of the rocky intertidal zone. While in the field at Cabrillo Point, I observed facilitative interactions between L.gigantea, L.scabra, and microalgae. Two field sites were created to investigate temperature differences between limpets with microalgae on their shell and those without. Limpets were studied for three days. At site and on each day, limpets with microalgae were .383 degrees Celsius warmer than limpets without microalgae. In addition, I discovered a significant main effect of site on the difference in temperature between limpet with algae and limpets without (p-value = .00451). My finding provokes further investigation of the interesting relationship between microalgae and limpet shell temperature.