"Cilophyte" otherwise known as "Cecaelia".
Are the type of merfolk that are half human and half octopus. Rumor has it; that they have magical powers, especially the kind that process and take control, transform, and they can even blend in to their surrounding.
And yet, no one on land has ever seen and lived to tell about it. They either have gone extinct, or the idea of such a creature like that existing could be just as they're describe as such, they are a Myth.
That said, a concept like that is still worth entertaining; Contrary to the Disney movies making villains out of them, there are those who would dress up as a Cecaelia. Having the lower part of their body from the waist down be nothing but tentacles.
Their costumes include... Tentacles of any color, length, and even the thickness of the tentacle. With waist sizes for an average build body, and even for those who happen to have a Plus-Sized body type. What ever they want; they sell!
Little did they know, with costumes such as these, they are also "Form Fitting". So for instance; if a skinny person end up with a Plus-Sized version of it, the person in question can simply grow into it, and the same can be said for the other way around. As well as some other side effects that may not have some importance. At least that's what they say...
But if costumes aren't your thing, then you can look at their trinkets.
ranging from necklaces and a statue.
A statue of a Fat male Cecaelia statue, a novelty item for sure, it may not be all that magical at all. But who knows...