Raxacoricofallapatorian

Raxacoricofallapatorians are a fictional alien race from Doctor Who. They are a humanoid species originating from the planet of Raxacoricofallapatorius with a biology made up primarily of calcium.

Biology
Raxacoricofallapatorians are bulky, humanoid creatures with fat, bulbous bodies. They have brown-green skin, no hair, and baby-ish faces with large black eyes. They have a pair of long arms that end in four clawed digits. They are known to reproduce by laying eggs, which appear as leathery orbs with several tendrils.

The internal biology of Raxacoricofallapatorians was rather complex, but it is known that they are largely calcium-based life-forms. Females of the species were capable of producing poisons within their bodies that could be expelled through their breath or by dart-shaped growths projected from their fingers. Due to their calcium-rich biology, Raxacoricofallapatorians reacted violently to acetic acid. Being splashed with vinegar was enough to make a Raxacoricofallapatorian explode and acetic acid was known to be used on Raxacoricofallapatorius as part of their people's execution process for criminals. Although Raxacoricofallapatorians are calcium-based, they have shown that they have hardened digestive systems that can process most carbon-based foods.

While quite bulky in stature, Raxacoricofallapatorians were capable of great bursts of speed and were considerably stronger than humans. One swipe from their claws was enough to decapitate a human. They also had a heightened sense of smell, able to detect elevated perspiration from distant prey.

As Raxacoricofallapatorians age, their bodies calcify until they become as hard as stone.

Society
Raxacoricofallapatorian society centred around several major families, including the Slitheen, Blathereen, Slavereen, Caizeen, Lilieen, Rackateen, Chippeen, Fittereen, Hanazeen, Glizeen, Hostrozeen and Arlene. Raxacoricofallapatorian names were complex with the various hyphenation showing their exact placement on the family lines. Their homeworld was governed by a Grand Council, overseen by the Lord Predator.

Unlike the Slitheen and Blathereen families, most Raxacoricofallapatorians were a peaceful race that taught their children maths and poetry. They made their homeworld a paradise for them and other peace-loving species and some of them were brilliant farmers, but they despised criminal members of their species and punished them without mercy.

Particularly dangerous criminals on Raxacoricofallapatorius were sentenced to death for their offences with no chance for appeal. Executions were public and involved the offenders being lowered into a cauldron of acetic acid and slowly boiled and liquefied.

Technology
Raxacoricofallapatorians had more advanced technology than humans by the 21st century. They had already achieved faster-than-light space travel, utilized teleportation technology and possessed advanced knowledge of genetic engineering. The most notable example of Raxacoricofallapatorian technology is the compression-field collar: a device worn by some members of their species when they infiltrate planets where the local population is physically smaller. When the Slitheen family came to Earth, they used these compression-fields to partially shrink their bodies so that they could fit into human disguises. They made these disguises from the skins of larger humans. Their size was controlled by the movement of gas, which caused a condition similar to farting, but with a smell slightly similar to that of bad breath due to calcium decay.