What is the effect of minimizing the within-cluster sum of squares on the shapes of clusters produced in K-Means?

Using an objective function that minimizes the within-cluster sum of squares (WCSS) causes K-Means to produce spherically shaped clusters. If it makes sense to find globular clusters within the data, K-Means performs quite well and is an appropriate way to cluster it; however, if it makes more sense to find elliptical clusters or irregularly-shaped clusters in higher-dimensional space, K-Means is usually not the best choice.