$ perl -E '
    use strict;
    use warnings;
    use utf8;
    use open OUT => qw{:encoding(UTF-8) :std};
    use Unicode::UCD "charinfo";

    say "\x{B5} = ", charinfo(0xB5)->{name};
    say "\x{BC} = ", charinfo(0xBC)->{name};
    say "\x{3BC} = ", charinfo(0x3BC)->{name};

    my $contents = "\x{B5} \x{BC} \x{3BC}";
    print "Original \$contents:    ";
    say $contents;
    print "Non-desctructive s///: ";
    say $contents =~ s/[\x{B5}\x{3BC}]/u/gr;
    print "Unchanged \$contents:   ";
    say $contents;
    print "Non-desctructive y///: ";
    say $contents =~ y/\x{B5}\x{3BC}/u/r;
    print "Unchanged \$contents:   ";
    say $contents;
'