You added a Battle Talus sculpture to Kilton's collection, and now Kilton would like to add a Frox sculpture.
Quest Location
You can start this quest by talking to Kilton in Tarrey Town after you complete A Monstrous Collection III.
Photograph a Frox
If you have completed Presenting: Sensor +!, you can set the sensor to search for Froxes if you have already added it to the Compendium and you no longer have a picture. Froxes can be found in the Gerudo Highlands Depths and the Central Hyrule Depths.
Quest Reward
Kilton gives you the Monster Saddle.