Blockchain technology can increase visibility in supply-chain transactions and lead to more accurate tracing of goods as well as provide evidence of whether a product is authentic or not. A shared, distributed ledger or blockchain alone, however, does not guarantee correct and trustworthy supply-chain traceability. We argue that blockchain technology (and any other digital traceability solution) must be enhanced with methods to anchor physical objects into information technology, Internet-of-Things and blockchain systems. Only when trust from the digital domain is extended to the physical domain can the movement of goods be accurately traced (e.g., for callbacks and provenance) and product authenticity determined. In this paper, we introduce the concept of crypto anchors, propose a classification and system architecture, and give implementation examples for different use cases and industries.