Stone sculptures are vulnerable to biological degradation caused by microorganisms, algae, lichens, and moss. To preserve these artworks, follow these proven methods:

1. Regular Cleaning: Use soft brushes and distilled water to remove surface dirt. Avoid harsh chemicals that may erode the stone. For stubborn growths, apply a mild biocide solution approved for stone conservation.

2. Protective Coatings: Apply breathable, water-repellent sealants like siloxane or fluoropolymer-based products. These coatings prevent moisture retention, a key factor in biological growth.

3. Environmental Control: Maintain stable humidity (below 60%) and temperature in indoor displays. For outdoor sculptures, ensure proper drainage and avoid shaded, damp locations.

4. Anti-Microbial Treatments: Use specialized treatments containing quaternary ammonium compounds or nano-silver particles to inhibit microbial colonization without damaging the stone.

5. Professional Inspection: Schedule annual assessments by conservation experts to detect early signs of degradation and implement targeted interventions.

By combining these approaches, you can significantly extend the lifespan of stone sculptures while preserving their artistic integrity. Always test new treatments on inconspicuous areas first and consult conservation professionals for valuable artifacts.