Mammon Machine (Pocket Dimension)
By far, the strangest aspect of the Black Omen is the Mammon Machine's function there. Though the machine appears damaged on the outside, Crono and his crew are 'thrown' into the machine, where it appears to be in a pocket dimension and wholly intact. What is the cause?
Queen Zeal throws the party into the Mammon Machine. Now, the machine is made of Dreamstone, and other objects made of Dreamstone by Melchior (including the Masamune and possibly the pendant) have corresponding Dream Species equivalents. Perhaps being thrown into the Mammon Machine meant the party would fight the Mammon Machine's untouched dream equivalent of itself. Masa and Mune can appear at the Denadoro Mts even though the Masamune is broken, after all.
As for why the Mammon Machine's dream equivalent is itself and not a creature like the others, let's look at each case.
Masa and Mune were designed with two prerogatives in mind. The first was to protect the Masamune until a worthy person comes to claim it. The second was to provide companionship and direction to the wielder of the blade, to help him find his inner strength and awaken the true power hidden within the blade. Masa and Mune's personalities show courage, intelligence (to a point), and an understanding of what it means to be a hero. They were to be the spiritual guides to the owner of the blade.
The pendant's original design goal was never stated, but I feel it could be implied. I feel its original purpose was to aid in interfacing with the the artifacts of Zeal, to aid in the activation and control of the Mammon Machine, and possibly to amplify magical power. As the Pendants design goals had multiple layers, the spirit within as well. Doreen was designed to compliment both the usages of the pendant, but also to compliment the user of the pendant. The pendant was crafted for the royal family of Zeal, and Doreen's talents were designed with this in mind. As such Doreen has a sharper mind then her siblings, and is well versed in philosophy as we see during Chrono Trigger. She appears to be more mature and serious then her siblings as well. All these facts point to her role being as an adviser to the owner of the pendant. Doreen's design goal was to advise the owner of the pendant so that its power would not be misused.
The Mammon Machine was crafted from Dreamstone to draw energy from a powerful new source the guru's had identified (they we later realize is Lavos). The Machine radiates the energy from the actual mechanical shell, but it must be drawing the power from Lavos somehow. The Mammon Machine spirit was designed to be the second end of the machine, to draw the power from Lavos itself and shunt that energy to the physical side of the machine in Zeal. The spirit was formed to resemble the physical Mammon Machine because it was providing the same function but in reverse (absorbing Lavos's energy rather then radiating it out). Unlike Masa, Mune, and Doreen the Mammon Machine's spirit didn't require a complex mind to complete it's job, so Melchior chose not to give it a full mind. It understood the workings of it's job, and the basics of defending itself.
Pocket Dimension Apparatus
Under the Pocket Dimension theory, the Mammon Machine actually dipped into Lavos's pocket dimension to tap his source. As a result, it had two interfaces; one for the outside world, and one for collecting energy from Lavos. After the Mammon Machine was removed and its link to Lavos cut, it still generated its own Pocket Dimension "field."
From: Theory (Objects)