Aalto University - MPS - Nordita consortium of scientists, led by Petri Käpylä, was awarded with 20 million CPU hours of PRACE Tier-0 resources in Mare Nostrum. The computational project studies the fundamental physical processes leading to the formation of sun- and starspots in the turbulent convection zone. Such processes have previously been related to strong shear layers deep in the stellar interiors, in the transition region from rigidly rotating radiation zone into a turbulent differentially rotating convection zone. However, recent observations show that fully convective stars exhibit magnetic activity levels similar to stars with convective envolopes. This puts the prevailing scenario under serious doubt. Our computational project searches for alternative explanations arising from turbulent effects.