For any conversion problem like this Google is an easy place to get answers.

Google [8.55 acres] and you get the answer in m²

Google [8.55 acres in square feet] and you get that instead.

If asked, Google would convert for you into square picas or square parsecs. It cannot itself convert into arpents (the weirdest area unit I could think of to test it on) but lists sites that give the conversion factor.

Good Hunting!
RD

PS: The arpent is a pre-revolutionary French unit used in Louisiana and Quebec until last century - recall Voltaire's dismissal of Canada as "quelques arpents de neige", "a few acres of snow". A Quebec version of Trivial Pursuit is called "Quelques Arpents de Pieges", "A Few Acres of Traps"!