Definition of echini:
(n) :
A sea urchin.
(n) :
(architecture) The rounded moulding forming the bell of the capital of the Grecian Doric style, which is of a peculiar elastic curve.
(n) :
(architecture) The quarter-round moulding (ovolo) of the Roman Doric style.
(n) :
(architecture) The egg-and-anchor or egg-and-dart moulding, because often identified with the Roman Doric capital.