Other common manipulable tactile objects include rubber toys stuffed with treats. The evolution of human consciousness is a tangibly manipulable process. Symbols consist of first-level objects and are directly manipulable by user code. A smaller variety, simple hand puppets often have no significant manipulable parts at all. "Directed differentiation" provides a potentially unlimited and manipulable source of cell and tissues. His illiteracy made him manipulable and vulnerable to their control. In summary, the Master Pyraminx has 30 "manipulable" pieces. Sometimes special variants exist with additional manipulable parts&colon; (e.g., eyelids that open and close).