1. INTRODUCTION
2. DETECTION AND SIMULATIONS OF SHELLS IN DWARF GALAXIES
2.1. Observed sample
2.2. Numerical simulations
3. OBSERVED AND SIMULATED SHELL PROPERTIES
4. DISCUSSION
4.1. A dry merger origin of the shells
4.2. A weak interaction origin of the shells
4.3. Comparison with Fornax dwarf galaxy
4.4. Cluster membership of the dwarfs with shell features
4.5. Dwarf-dwarf mergers in the Virgo cluster
4.6. Conclusion