There had been rumors, for a while now, that the population of crabs around the bay was infected by a strange disease.
Crabs that had been caught and prepared for food would keep on moving, and those who dared eat suffered from aching stomaches, and nausea.
The crabs will return to unlife after death, and go on with whatever crabs usually do.
It is not known wether the disease spreads to humans, or demi-humans, but a team of experts has been assembled to investigate the cause, and possible consequences for the surrounding environment should the whole crab population become extinct - or worse, come back to unlife.
# of Appearance: 1d6 to 5d20.
Normal crabs become zombified, after a successful attack by a zombie crab. They might swarm places just as if they were alive, and attack other crabs, and small animals, feed on plants, fruit, and whatever they find.
If threatened they will flee, if cornered, or picked up, they will attack using their pincers. Although they will not do sufficient damage to justify the loss of hit points, the larger ones might cut off fingers, and such, so beware! The undead pincers can cling fast to fingers, hands, or noses, even if the pincer is torn from the crab's body.
Zombie Crab, Giant
Giant zombie crabs defend themselves if cornered, or threatened. Use the reaction table when the PCs encounter a giant zombie crab.
Reaction Table (2d6)
2 - The crab will attack the PCs one after another, fiercely using its pincers to cut its opponents to pieces, then berserkly tear apart trees, furniture, and itself.
3-4 The crab will attack and feed on the PCs.
5-6 The crab will attack.
7 The crab will wait motionless until the PCs interact with it in one way, or another. If so, roll again.
8-9 - It will move a little away from the PCs.
10 - It will move towards the PCs, eye them (if eyes are still intact), then back away again.
11 - It will snap its pincers rhythmically, then move along.
12 - It will perform a little crab dance, circle around the PCs, then scuttle off in a random direction.
Zombiefied Stat Block
You can look up the stats for giant crabs on page 63 of the Basic Fantasy RPG (2nd Edition), or page 65 of the 3rd Edition release R78. Just modifiy the following stats.
Movement: is divided by two for the average giant zombie crab; and some are slower due to missing limbs.
* Note that the cause of the disease must yet be investigated, and there are still no known cases of humans, or demi-humans being infected.