Sticking with the stone motif I engraved Limestone Pie, Pinkie Pie’s irritable sister into another slate.
 
Of all the characters who were introduced but didn’t get any real spotlight so far I think Limestone Pie may be the one most in need of an episode focused on her. Ever since the episode “The Gift of Maud Pie” established that Pinkie Pie has a special day with each of her sisters every year at a different location I have been hoping for episodes with a focus on Pinkie’s other sisters (it is hard to imagine the makers of MLP would set the stage for such episodes which could play pretty much anywhere with little need for further exposition without making use of it at some point).We have since seen Marble and Limestone Pie as supporting characters in “The Maud Couple” and Limestone was practially begging for an episode focused on her in this one. While shy and silent characters like Marble have gotten attention in MLP many times already I think Limestone is a rather unique character in MLP. The Pie sisters seem to represent the four tempraments (sanguine, phlegmatic, melancholic, choleric) with Limestone playing the part of the choleric. I don’t think we have had a truly choleric character in MLP so far. There may be Spitfire, but for her it seems to be mostly the job requriement (though she enjoys it) and Cranky (but honestly, Pinkie was really pushing him to loose his composure and only after a long time).  
More importantly Limestone said some things in “The Maud Couple” which were quite remarkable. First she revealed for herself to be jealous of Maud for having found a very special somepony (by fiercely denying any jealousy when nopony else had even brought up the suggestion that she was jealous) and then, when Pinkie Pie was crying her eyes out Limestone said: “Buck up, Pinkie Pie. You look as miserable as I feel all the time!” (here is the entire scene for reference).  
This is one of the saddest things said by any character in MLP so far and Pinkie Pie, the pony whose main purpose in life is to make everypone else happier… ignored it completely.I can only imagine that either Limestone is one of those characters who cannot be happy unless they are feeling miserable and that Pinkie knows this and is therefore not shocked by Limestone’s revelation or (more plausible in my opinion) that Pinkie was just too preoccupied with her own troubles with Mudbriar to give Limestone’s words the attention they deserved.Limestone wants to take the whole responsibility of the Rockfarm. Work there is often emphasised to be hard and exhausting and managing the farm is not likely to get any easier for Limestone with the parents getting older and with Pinkie and Maud having left the farm. A statement given by Trixie in “Magic Duel” suggests that working on a rock farm is not seen as a job most ponies would strive for and the farm sure seems to be rather isolated. For all their traditions joy and happiness doesn’t seem to come in abundance on the rock farm (as suggested by the story of how Pinkie got her cutie mark).  
With all that in mind I really think that Limestone Pie should definitely get some attention for her unique character and a rather rare situation in the usually so uplifting land of Equestria.