MissingNo. (Fossil Aerodactyl form)
The second skeleton in the Pewter museum has a wilder silhouette than the first, all wingbone and jaw, and index 183 lets you fight it. Same trick as its Kabutops sibling one slot down: the sprite loader carries a hardcoded exception for this index, written so the museum could display an Aerodactyl fossil, and a wild encounter walks straight through the exception like a propped-open door.
Under the wings it is pure MissingNo., zero in the Pokedex byte and everything that follows from it. The chart-breaking 136 attack, the 0 defense, Water Gun twice and Sky Attack once, catch rate 29. If you have read the other MissingNo. files, you already know this creature. You have just never seen it look like the shadow of a pterosaur.
One detail worth savoring: the Aerodactyl fossil sprite is a tile larger than the Kabutops one, 7 by 7 against 6 by 6, which makes this the biggest-bodied MissingNo. in the game. The most fragile creature in Kanto, wearing the most dramatic corpse in the museum.
BIRD NORMAL
The bytes
| What | Where in the ROM | Value |
|---|---|---|
| Index number | slot 183 of the species table | 0xB7 (183) |
| Pokedex byte | 0x410DA | 0 (no real Pokemon is 0, so the game improvises) |
| Stats entry | 0x39FC2 (entry 255: unsigned byte math on dex 0) | 00 21 88 00 1D 06 06 00 1D 8F... |
| Size byte | entry byte 10 | 0x88 = 8 wide, 8 tall (the buffer holds 7x7) |
| Name bytes | 0x1C93A | 8C 88 92 92 88 8D 86 8D 8E E8 |
| Catch rate | entry byte 8 | 29 |
Front sprite pointer 0x1900 resolves into ROM bank 0 (deterministic) at file offset 0x1900. The decode is deterministic: it looks the same on every cartridge, every time.
Byte for byte identical in Blue.
Base stats
Its stat spread, straight from the entry bytes. Glitch specimens love extremes, a wall with zero attack, or a paper-thin speedster.
Moves
Knows from the start: WATER GUN, WATER GUN, SKY ATTACK.
Learnset (read straight from its pointer)
| Level | Move |
|---|---|
| Nothing. Its learnset pointer leads nowhere useful. | |
TM and HM compatibility (flag bits, entry bytes 20 to 26)
| Machine | Move |
|---|---|
| TM01 | MEGA PUNCH |
| TM02 | RAZOR WIND |
| TM03 | SWORDS DANCE |
| TM05 | MEGA KICK |
| TM06 | TOXIC |
| TM09 | TAKE DOWN |
| TM10 | DOUBLE-EDGE |
| TM11 | BUBBLEBEAM |
| TM13 | ICE BEAM |
| TM14 | BLIZZARD |
| TM17 | SUBMISSION |
| TM19 | SEISMIC TOSS |
| TM20 | RAGE |
| TM25 | THUNDER |
| TM26 | EARTHQUAKE |
| TM27 | FISSURE |
| TM29 | PSYCHIC |
| TM30 | TELEPORT |
| TM43 | SKY ATTACK |
| TM44 | REST |
| TM45 | THUNDER WAVE |
| TM49 | TRI ATTACK |
| HM01 | CUT |
| HM02 | FLY |
Evolutions
| Trigger | Becomes |
|---|---|
| None. This creature is final. | |
The glitches with a face
Almost every creature in here wears whatever your Game Boy last drew, a smear of borrowed video memory. These three do not. Their index numbers happen to point at real, finished sprites the game keeps around for other reasons, so alone among the glitches, they have a face somebody actually drew.
That is the whole difference. Not new art, just a glitch whose broken pointer landed on a picture instead of on noise.
Hear its cry
A cry is three bytes the game looks up by index number: a base sound, a pitch, and a length. This specimen reads its three bytes straight from the table. I rebuild the sound live from the Game Boy's two pulse channels and its noise channel. This is not a recording.
Does it still work?
This is the question people actually ask about a glitch, so here is the honest answer for this one.
| Where | Still works? |
|---|---|
| Original Game Boy cartridge | Yes. The source of every byte on this page. |
| Game Boy Color / Super Game Boy | Yes, with the auto-assigned palette shown above. |
| 3DS Virtual Console (2016 re-release) | Yes. Nintendo shipped the re-release unpatched, so this is the most accessible way to reach it in 2026. |
| Later remakes (FireRed, Let's Go, and newer) | No. Rebuilt engines, the empty-slot overflow that produces this creature is gone. |
Fight it yourself
This is our from-scratch recreation of the Red battle engine. The enemy team is preset to this specimen; pick your own fighter, glitch or otherwise.
Every number on this page was read from a Pokemon Red ROM by reproducing the game's own out-of-bounds memory reads. Nothing is invented. Part of The Glitchhouse.