Historical clue formulations

• Like the rotation of the earth — 2016-12-01
• Kind of skeleton — 2012-06-14
• Like some symmetry — 2011-05-18
• Like some symmetry — 2010-08-16
• Kind of skeleton or symmetry — 2008-04-26
• Kind of skeleton — 2005-08-13
• Having a line of symmetry — 2004-08-01
• Like some symmetry — 2004-06-21
• Like some rotations — 2004-06-06
• Like some symmetry — 2003-05-07
• Kind of skeleton — 2002-03-23
• Variety of symmetry — 1999-09-28
• Kind of skeleton — 1999-06-25
• Perpendicular to radial — 1999-05-20
• About the line of rotation — 1998-06-30
• Kind of symmetry — 1996-10-12
• _____-flow turbine — 1995-06-11
• Having a line of rotation — 1995-04-04
• The A in "CAT scan" — 1994-02-23