In this chapter, we report the different natural examples, where the interaction of a solid phase change with a fluid flow generate specific patterns. We focus our review mainly to the cases of dissolution/precipitation and melting/solidification of a pure substance. We classify the patterns by the type of hydrodynamic flows. First, in absence of imposed flow, the phase change can create a gravity driven flow, with stable or unstable density stratification. Second, a flow can be imposed externally and we will distinguish deep flows and shallow water flows, for which the dynamics of the free-surface matters. Although the time and space scales can vary by several orders of magnitude depending on the material experiencing the phase changes, some characteristic patterns appear to be generic, arguing for physical or geometrical mechanisms to explain their emergence. The same mechanisms often apply to both dissolution/precipitation and melting/solidification.