Answer:

fossils

Answer	Crossword Clue
FOSSILS	Old-fashioned folk
FOSSILS	Traces of the past
FOSSILS	Fuddy-duddies

FOSSILS	Dig discoveries
FOSSILS	Pieces of the past
FOSSILS	Outdated ideas
FOSSILS	They're decidedly out
FOSSILS	Archaeologist's finds
FOSSILS	Things of the past
FOSSILS	What paleontologists study.
FOSSILS	Old-fashioned persons.

FOSSILS	Museum displays
FOSSILS	Archeologists' finds
FOSSILS	Fogies
FOSSILS	Natural history museum sights