In today’s otherwise meh column, I wanted to compliment this truly brilliant response:
Thanks! 
I don’t think the column was humdrum, but hey I’m glad my comment got in.
This brings up a curious point, however: How the English parts of speech are somewhat arbitrarily classified.
I was always taught, as far as I can remember, that the possessive forms of pronouns (“his”, “my”, “their”, etc.) are pronouns. A long time ago, I noticed on my own that possessive forms (of nouns or pronouns, like “John’s house”) function as adjectives because they modify other nouns.
That, of course, is exactly Una’s point in calling “their” an adjective. But I was always taught that they are classified as pronouns.
I love the mixed fruit columns.
Most contemporary teaching and most contemporary reference books are wrong on this point. The truth is that “my”, “thy”, “her”, “our”, “your”, and “their” are possessive adjectives, while “mine”, “thine”, “hers”, “ours”, “yours”, and “theirs” are the genitive cases of the personal pronouns; “his” and “its” can be either. The distinction is a fairly common one, found in most European languages, and pretending that it isn’t there in English achieves nothing but confusion of English-speaking students when they try to learn other languages.
And it’s threads like this that keep the SDMB alive!
Oh, these, and pitbull threads, kittie pics and trolls…but mostly these!
Bravo indeed Una.
Una remains a consistently high-quality poster. That answer was simply glorious. 
The sponge question seemed like an XKCD What-If.
“Is there a god” … it’s an adverb is you spelt it correctly
“There” is an adverb, an adjective, and a noun, actually.
Uh, . . . Didn’t you know? Randall Munroe IS Cecil!