What were the capital abacus and echinus?

The capital abacus and echinus are architectural elements found in classical columns. The abacus is the flat, rectangular slab that sits atop the column, serving as a support for the structure above. The echinus is the rounded, cushion-like section beneath the abacus, often embellished with intricate designs. Together, these elements contribute to the overall aesthetic and structural integrity of classical architecture, particularly in the Doric, Ionic, and Corinthian orders.