Please help me identify a module

[Lanathar]

I have recently been recalling a module/adventure I was a player in during the very early days of playing pathfinder. Given this it would probably have been from 2010 or earlier...

There was some kind of investigation going on and I feel like thier were Chuuls

The key memory was there was some horrifying sea creature in the water that grew in power the more days it was left unidentified. By the end it was Colossal and had Implosion as a spell like ability and was impossible to defeat

Our GM showed us the print page that explained what happened if it was left to grow for weeks. So it wasn't homebrew (although it was adapted to fit a homebrew setting).

Has anyone heard of this module?
It might not even be Pathfinder.

I suddenly had the urge to work out what this adventure was

[GeraintElberion]

It sounds a bit like From Shore to Sea in terms of Chuul and whatnot.

Or it could be Raging Swan's Sunken Pyramid?

[Robert Ranting]

Richard Pett's infamous adventure The Styes from Dragon #121 seems fairly similar, although the creature in question doesn't have implosion as written.

Styes Spoilers:

The adventure involves a plot by an aboleth (which utilizes human, skum and chuul minions) to corrupt a sea side city and fuel the growth of a fiendish kraken. If the PCs act quickly, it is only huge, but left unchecked it will grow to a colossal size with 60HD, packing various nasty spell-like powers.

[Tinalles]

Could it be Wake of the Watcher, the fourth book of Carrion Crown? It was published in 2011, so not TOO far from your estimate.

Note that the following spoils the adventure pretty thoroughly.

Spoiler:

The adventure involves investigating a creepy coastal town called Illmarsh. There's a chuul with class levels guarding a shrine, and the adventure revolves around investigating and uncovering the town's horrific relationship with a group of skum: they regularly send their girl children down into the sea to be fish-wives.

The final boss is horrific mold-thing called a Dark Young of Shub-Niggurath. It doesn't have implosion, but if not killed, its mama -- Shub-Niggurath herself, the Goat with a Thousand Young, all praise, ia ia! -- manifests in the bay. Which is officially Bad News.

[Lanathar]

Robert Ranting wrote:

Richard Pett's infamous adventure The Styes from Dragon #121 seems fairly similar, although the creature in question doesn't have implosion as written.

** spoiler omitted **

Thanks. This is the one

It looks like when the thing increased to 20HD my GM read off the 20 HD abilities for a half fiend rather than a fiendish creature and that grants "destruction" which must be my confusion

Still seems like it was incorrectly done.

Memorable though