Sometimes I pick in some discussions hints about a "Tarrasque planet". Is it an official place? Was it published in what book / magazine / source material?
P.S.: I know the default stance is to take sources like Dragon Magazine as unofficial reference material, but for the scope of this question so long it was published or licensed by the copyright owners, it is "official".
Best Answer
The crystal sphere Falx
Featured in 2nd edition D&D's Spelljammer book Practical Planetology, the planet Falx is an Earth-like planet with a single large continent and a high carbon dioxide concentration.
It is populated with hundreds of creatures that are very similar to the tarrasque, but are not the tarrasque. I cannot find a particular image or description of how they are different; from memory, they are smaller.
The book features 5 different adventure ideas for the planet, and mentions a variety of other threats (myconids, illithids, mobile plants) but the one everyone remembers is the tarrasque analog.