A while back, I ate an avocado that, when I cut it up, had a seed that, instead of being large and round, was shaped like an almond and not much bigger.
More yummy avocado flesh for me! 
Anyway, why would that be? My guess was that the embryonic avocado wasn’t fertilized but a fruit developed anyway; anyone here who knows more about botany than me have an answer?
Don’t need one right away. 
I find it more likely it’s just a freak developmental error.
If one could grow a strain of small pit avocados, one could make a lot of money.
From Wikipedia:
“In addition, due to environmental circumstances during some years, seedless avocados may appear on the trees. Known in the avocado industry as “cukes”, they are usually discarded commercially due to their small size.”
It seems that the big seed is considered an advantage in the market.
Here is a picture of an avocado “cuke”. Clearly does not look at all like a normal avocado, and wouldn’t make it to market. Seems unlikely that this is what the OP had.
You’re kinda buying a pig in a poke, so it makes sense that a big seed isn’t necessarily something to select against.
I’m always surprised that small avocados are so much cheaper than big ones (per amount of flesh). I think small avos are superior because the ideal amount of avocado to prepare is a whole number of avocados, given how quickly they go bad once cut.
Mine did look like the bigger ones.
Presumably, “cuke” is short for cucumber, as that’s what the seedless one looks like.
Which is why I didn’t suggest it was a freak genetic variant.
The small avocados (typically the Hass variety from California) have a higher fat content by weight than the larger Florida avocados, and thus more calories per ounce.
I don’t mean buying a smaller variety, I mean buying smaller fruits of the same variety
I live in California, and when I buy avocados (usually Hass) from farmers markets or roadside stands, I can get twice as much avocado flesh per dollar by buying small avocados. There’s a price premium for larger ones that doesn’t make sense to me.
If the uneaten skin thickness remains the same, it increases as the square of linear dimensions, wherease the amount of flesh increases as the cube. So the proportion by mass of edible flesh to uneaten skin is probably lower for smaller avocados.
