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.
Buy the Tears of the Kingdom Zelda amiibo
Buy The Legend of Zelda: Tears of the Kingdom for Nintendo Switch