logic.rb

class Cat
  def self.all
    ObjectSpace.each_object(self).to_a
  end
end

class Animal
  attr_accessor :all
  def initialize
    @all = []
  end
end

animals = Animal.new

3.times do
  animals.all << Cat.new
end

Cat.all.any? {|i| animals.all.include? i}
Cat.all.all? {|i| animals.all.include? i}
animals.all.any? {|i| Cat.all.include? i}
animals.all.all? {|i| Cat.all.include? i}