A classic diminutive suffix in Ancient Greek is -ίδιον, which forms a neuter second noun.
But what happens when this is applied to a noun with a vowel in the stem? For a concrete example, if I wanted to talk about a "little sea monster" (using the noun κητε-), would that be a κητίδιον, a κητείδιον, or something else entirely?
(I'm most curious about Attic, with its patterns of vowel contraction, but answers for other dialects would be interesting as well!)