A very rare class, indeed. Polymorphs are fully liquid Canmephians, able to take any shape and color. For Drygers, this is above and beyond the origional ability to change between draconic and feline forms.
Internal Anatomy (Nodes and density)
A polymorph's internal structure comprizes of multi-purpose cells organized into groups called "nodes". Each node, while physically small, is self contained and can serve numerous functions. It also serves as a small computer server, thus making a polymorph a rather massive organic Beowulf cluster.
Nodes may crowd tightly among each other, forming various needed "psudo-organs" such as digestion or fluid transmission. Nodes may be very tight, forming dense bone-like structures, or very loose, forming various tissues like muscle.
Nodes can recognize each other, so if a polymorph is physically seperated the two peices can recombine easily.
Nodes can grow hair/fur.
Every cell has a genetic default form programmed in it's DNA, which allows nodes to form a full body with very little effort/energy needed to maintain the form.
Every node is seemingly programmed with one of two "operating systems" which is above the native DNA programming: Linux or FreeBSD. All nodes must have the same operating system or the polymorph will split along OS lines.
Polymorphs cannot spontaneously add mass they do not have, nor can they subtract mass they may have into nothingness. The use of a pocket-dimentional "black hole" is nessisary. The current limitation of such items are 64 tons of mass under Sol 3/Canmeph 2 gravity.
A polymorph will eat a rather large meal, three times a day, to sustain itself under it's genetic default morph. Depending on the morph, this can change dramatically.
A polymorph with a mass reserve can pull energy from said reserves, but it is highly unrecommended. The side effect of having a mass reserve is that the polymorph will never feel hungry, but also will never feel full. The mass reserve, unfortunately, will burn itself off over time, requiring the polymorph to occassonally refill it.
Polymorphs will burn energy to maintain their morph. The further they deviate from their genetic default, the more energy they burn.