Mirelurk

“Most Mirelurks are heavily armored and resistant to most forms of damage, but their faces are vulnerable.” — Fallout 4 loading screens
A mirelurk refers to any one of three mutated crustaceans that dwell in the swamps of the Commonwealth and commonly found around the Island in 2287.
Background Mirelurks have the dubious distinction of being one of the first radioactive mutants to emerge into the world, as a result of widespread radioactive pollution of the environment by United States megacorporations such as Poseidon Energy and General Atomics. Environmental organizations such as Nahant Oceanological Society, dedicated to saving the oceans, attempted a variety of last-ditch efforts to raise awareness of this problem and encourage radical action to curtail environmental destruction at the hands of reckless corporations. However, their efforts were in vain. Ignored by authorities, to the point where they refused to even take their phone calls (as was the case with the Boston Port Authority), they attempted to garner attention by reporting the situation to the Galaxy News Network. The media ignored their reports as well, except for running a story about the upcoming shellfish season and how great it was going to be. Of course, it neglected to mention that the average increase in mass on the order of 14% in crabs and 12% in lobsters meant that the available food supply would run out quickly, leading to colony collapse and localized extinction.
Although the Great War put an end to corporate pollution, it was replaced by overwhelming amounts of nuclear fallout instead. In the ensuing melting pot of mutations, the modern mirelurks emerged. Attempts to classify the resulting creatures have proven difficult. The crab mirelurk, for example, contains multiple phylum markers from two distinct and unrelated species: The Atlantic Horseshoe Crab (Limulus polyphemus) and the Atlantic Blue Crab (Callinectes sapidus). As such, it would be necessary to catalog it simultaneously as belonging to the Crustacea and the Chelicerate phylums, with the simultaneous classification of two distinct classes (Merostomata and Malacostraca). As such, wasteland scholars generally assign it its own classification: Scylla serrata horrendus. The knowledge that mirelurks were much smaller before the bombs dropped and mutated them still persists among some wastelanders in the Commonwealth. Mirelurks are also known to have a pronounced sensitivity towards white noise, as seen in Vault 92 and on Spectacle Island.
Although mirelurks tend to inhabit polluted rivers, coastal waters, and sewers, their meat is considered a delicacy among wastelanders. Mirelurk hunters or herders can count on a steady demand for their meat and make a high profit selling it to wasteland traders. However, the size of the meat market means competition is stiff and suppliers can be targeted by rivals attempting to knock them out of the market (sometimes literally). They also grow remarkably fast, requiring just a few weeks for them to reach maturity. If corraled and domesticated, mirelurks can be a flexible supply of food. The Free States did, in fact, entertain such an option.
Mirelurks can also be a blight on permanent settlements, as is the case with Rivet City. Mirelurks nesting below inhabited decks are a continued nuisance for denizens of the city, despite regular extermination operations by the city's security team. Infestations are made even worse by the fact that mirelurks have adapted to lay their eggs in multiple small nests throughout shallow water (unlike pre-War crustaceans that adhered their eggs to their body if disturbed, the larval mirelurks within exhibit incredible predacious behavior and are ready to attack if need be.
Biology Most adult mirelurk variants have shells and pincers resembling those of horseshoe crabs, while their offspring resemble mole crabs. The queen, on the other hand, has a shell that resembles that of a giant isopod or spider crab. The hunter variant appears to be a lobster. Finally, the mirelurk king is unique in that it bears no resemblance to any sort of crustacean.
All mirelurks (excluding mirelurk kings and softshell mirelurks) are protected by a thick shell that is difficult to penetrate, even with powerful ballistic weapons. The face is unarmored but a small target, and when charging a mirelurk will often lower its head to protect this area. However, the face will inevitably be exposed once the creature commences close combat. Extremities are also more vulnerable than the rest of the body, though not as much as the face.
Typical specimens, in particular, resemble mirelurk hunters from the Capital Wasteland but also differ in several aspects, such as is seen with their legs. This specimen also walks in a mixed crab/spider-like motion, which is atypical of mirelurk variants documented so far; in general, they have more realistic qualities correlating to appearance.
Gameplay attributes Mirelurks will bury themselves in dirt or mud, with the only visual indication that they are present is the rounded backs of their shells, which resemble large, smooth rocks from a distance. They can also submerge themselves underwater when needed. V.A.T.S. will be able to detect them from a distance when used. It is not uncommon to see mirelurks with netting and seaweed caught on their carapaces or have barnacles latched on to them. Typical mirelurks and their variants can occasionally be found feeding on sea creatures.
Mirelurks are mostly found in groups and thus often utilize strength in numbers. Glowing mirelurks also deal radiation damage when in close quarters. Combine this with their generally high resilience and they can easily prove a challenge for low-level player characters.
Because of their thick shells, they can be quite hard to defeat in a melee fight, as they tend to hide their weak points when the player character is about to strike, or when they charge before revealing their body parts in order to attack. Because of their unique fighting style, melee weapons with the legendary modifiers "penetrating" (attacks ignore 30% of enemy's damage resistance) and "exterminator's" (specific bonus damage to mirelurks) are very useful against them.
As some companions mention, mirelurks have no way to protect themselves against mines, or any attack from below. All mirelurk variants have a chance to be pacified through the Wasteland Whisperer perk.
Variants
Mirelurk hatchling
Mirelurk spawn
Nukalurk spawn
Softshell mirelurk
Mirelurk
Mirelurk razorclaw
Mirelurk killclaw
Glowing mirelurk
Nukalurk
Bloodrage mirelurk
Mirelurk queen
Nukalurk queen
Hunters
Mirelurk hunter
Glowing mirelurk hunter
Albino mirelurk hunter
Nukalurk hunter
Kings
Mirelurk king
Mirelurk deep king
Glowing mirelurk king
Nukalurk king

SPECIAL ABILITIES
IMMUNE TO RADIATION: The hatchling reduces all Radiation damage suffered to 0 and cannot suffer any damage or effects from radiation.
LITTLE: The hatchling is smaller than most characters. The creature’s normal HP decreases to Body + 1⁄2 level (rounded up), but its Defense increases by 1. Further, it is slain by any hit that inflicts an Injury.
AQUATIC: The hatchling can swim and submerge itself in water indefinitely without needing to come up for air. They suffer no difficulty increase for attacks or movements made while underwater.
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