A blockchain AI refers to an artificial intelligence system that is built on a blockchain technology. It combines the benefits of both AI and blockchain to create a secure and decentralized AI system. As for the features/advantages of a blockchain AI, here are 15:

1. Transparency: The use of blockchain ensures transparency in the decision-making process of the AI system.

2. Security: Blockchain technology provides a high level of security, making it difficult for unauthorized access or tampering.

3. Decentralization: The AI system is not controlled by a single entity, but rather distributed across multiple nodes, making it more resilient to failures or attacks.

4. Trustworthiness: The immutability of blockchain ensures that the AI system's actions and decisions can be trusted.

5. Privacy: Blockchain AI can provide privacy protection by allowing users to have control over their own data.

6. Data integrity: The use of blockchain ensures the integrity of data, preventing any unauthorized modifications.

7. Efficiency: Blockchain AI can automate and streamline various processes, leading to increased efficiency.

8. Cost-effectiveness: By eliminating intermediaries and reducing the need for trust, blockchain AI can help reduce costs.

9. Scalability: Blockchain AI can handle large amounts of data and transactions, making it scalable for various applications.

10. Traceability: The use of blockchain allows for the traceability of data and transactions, providing a transparent audit trail.

11. Collaboration: Blockchain AI can facilitate collaboration between different parties by providing a shared and trusted platform.

12. Smart contracts: Blockchain AI can utilize smart contracts to automate and enforce agreements between parties.

13. Immutable records: The use of blockchain ensures that records cannot be altered or deleted, providing a reliable source of truth.

14. Real-time updates: Blockchain AI can provide real-time updates and notifications, enabling faster decision-making.

15. Interoperability: Blockchain AI can integrate with other systems and technologies, allowing for seamless interoperability.