A while ago, as some of you may remember, I embarked on a modding quest to create a completely indestructible creature. The end result of my labors was the fluffball, a living ball of fluff with no organs, blood, appendages, or functional tissue. These features made it nearly impossible to kill. Oddly, however, during my last fortress, I began to find fluffball corpses scattered around the halls. I dismissed this as a fluke and went on.
Later, after this fortress fell to a combination of many factors, I embarked on a sinister biome. There I saw something very odd: a swarm of zombie fluffballs. Their description contained the line "His/her body is gone." Intrigued, I went to the arena. There, I made a zombie fluffball and a dwarf. I took control of the dwarf, and when I tried to use an aimed attack on the fluffball, nothing happened. I don't mean that I missed, I mean that there was no body part to aim my attack at. I then tried a normal, unaimed attack, at which point DF promptly crashed. Because my fluffballs have no structural body parts, there was nothing for the zombie coding to leave behind.
Clearly, I have accidentally made something that is so invulnerable that just trying to harm it divides by zero and ends the universe.
If anyone wants to confirm my results, the raw file for the fluffball is here:
[CREATURE:FLUFFBALL]
[DESCRIPTION:An adorable ball of fluff.]
[NAME:Fluffball:fluffballs:fluffball]
[CASTE_NAME:fluffball:fluffballs:fluffball]
[CREATURE_TILE:'o'][COLOR:7:0:1]
[BIOME:ANY_LAND]
[BENIGN]
[LARGE_ROAMING]
[DIURNAL]
[MAXAGE:5:7]
[MUNDANE]
[NATURAL_SKILL:PROSE:10]
[PET]
CANNOT_UNDEAD - close this in brackets to "fix" the "error"
[COMMON_DOMESTIC]
[PETVALUE:30]
[TRAINABLE]
[LITTERSIZE:3:7]
[CHILD:3]
[GENERAL_CHILD_NAME:fuzzball:fuzzballs]
[FREQUENCY:100][POPULATION_NUMBER:20:60][CLUSTER_NUMBER:5:10]
[EXTRAVISION]
[FLIER]
[WEBIMMUNE]
[NOPAIN][NOEXERT][NO_FEVERS][NOBREATHE][NOSTUN]
[NO_DRINK][NO_EAT][ALL_ACTIVE]
[NO_THOUGHT_CENTER_FOR_MOVEMENT][NOBONES]
[NOT_BUTCHERABLE]
[PREFSTRING:fluffyness]
[PREFSTRING:adorable cuteness]
[PREFSTRING:sleeping dust]
[BODY_SIZE:0:0:100]
[BODY_SIZE:0:100:250]
[BODY_SIZE:1:10:500]
[BODY:BASIC_1PARTBODY]
[SPEED:1750]
[USE_MATERIAL_TEMPLATE:FLUFF:FEATHER_TEMPLATE]
[MAT_FIXED_TEMP:10067]
[STATE_NAME_ADJ:ALL:fluff]
[STATE_COLOR:ALL:WHITE]
[DISPLAY_COLOR:7:0:1]
[SOLID_DENSITY:1]
[USE_MATERIAL_TEMPLATE:POWDER:CREATURE_EXTRACT_TEMPLATE]
[MAT_FIXED_TEMP:10067]
[STATE_NAME_ADJ:ALL:powder]
[STATE_COLOR:ALL:WHITE]
[DISPLAY_COLOR:7:0:1]
[SOLID_DENSITY:1]
[MELTING_POINT:10000]
[BOILING_POINT:10002]
[SYNDROME]
[SYN_NAME:fluffy comfyness]
[SYN_AFFECTED_CLASS:GENERAL_POISON]
[SYN_IMMUNE_CREATURE:FLUFFBALL]
[SYN_CONTACT]
[SYN_INHALED]
[CE_DROWSINESS:SEV:300:PROB:90:START:5:PEAK:10:END:1000]
[CE_DIZZINESS:SEV:300:PROB:60:START:5:PEAK:30:END:1500]
[CE_NUMBNESS:SEV:300:PROB:30:START:5:PEAK:200:END:1500]
[CE_PARALYSIS:SEV:100:PROB:1:START:5:PEAK:300:END:5000]
[TISSUE:FLUFF]
[TISSUE_NAME:fluff:NP]
[TISSUE_MATERIAL:LOCAL_CREATURE_MAT:FLUFF]
[RELATIVE_THICKNESS:1]
[TISSUE_LEAKS]
[TISSUE_SHAPE:FEATHERS]
[VASCULAR:1]
[TISSUE_LAYER:BY_CATEGORY:ALL:FLUFF]
[ATTACK:FLUFF:BODYPART:BY_TOKEN:UB]
[ATTACK_SKILL:PROSE]
[ATTACK_VERB:fluff:fluffs]
[ATTACK_CONTACT_PERC:100]
[ATTACK_PRIORITY:MAIN]
[SPECIALATTACK_INJECT_EXTRACT:LOCAL_CREATURE_MAT:POWDER:POWDER:100:100]
[ATTACK_VELOCITY_MODIFIER:1]
[SECRETION:LOCAL_CREATURE_MAT:FLUFF:POWDER:BY_CATEGORY:ALL:ALL]
[MATERIAL_BREATH_ATTACK:LOCAL_CREATURE_MAT:POWDER:TRAILING_GAS_FLOW]
[SOUND:ALERT:200:1000:VOCALIZATION:squeak:squeaks:an alarmed squeak]
[SOUND:PEACEFUL_INTERMITTENT:10:1000:VOCALIZATION:purr:purrs:deep purring]
[CASTE:FEMALE]
[FEMALE]
[CASTE:MALE]
[MALE]
[SELECT_CASTE:FEMALE]
[USE_MATERIAL_TEMPLATE:MILK:MILK_TEMPLATE]
[STATE_NAME:ALL_SOLID:frozen fluff milk]
[STATE_ADJ:ALL_SOLID:frozen fluff milk]
[STATE_NAME:LIQUID:fluff milk]
[STATE_ADJ:LIQUID:fluff milk]
[STATE_NAME:GAS:boiling fluff milk]
[STATE_ADJ:GAS:boiling fluff milk]
[PREFIX:NONE]
[MILKABLE:LOCAL_CREATURE_MAT:MILK:200]
[USE_MATERIAL_TEMPLATE:CHEESE:CREATURE_CHEESE_TEMPLATE]
[STATE_NAME:SOLID:fluff cheese]
[STATE_ADJ:SOLID:fluff cheese]
[STATE_NAME:SOLID_POWDER:fluff cheese powder]
[STATE_ADJ:SOLID_POWDER:fluff cheese powder]
[STATE_NAME:LIQUID:melted fluff cheese]
[STATE_ADJ:LIQUID:melted fluff cheese]
[STATE_NAME:GAS:boiling fluff cheese]
[STATE_ADJ:GAS:boiling fluff cheese]
[PREFIX:NONE]
If you want to be able to embark with these on an evil biome, just close off the CANNOT_UNDEAD tag in brackets, so that it looks like [CANNOT_UNDEAD]
Also, feel free to share any similar experiences you have had with oversights in modding.