The next category of Muktze is known as Muktze Mahmat Gufo, or something that is inherently Muktze. This refers to objects which do not have the status of a Kli and have no purpose on Shabbat, and save for some extraordinary circumstances, can never be moved on Shabbat. Some examples of this category include stones or money.
In a related manner, the Shulhan Aruch (O.H. 308:29) discusses the Muktze status of foods that are eaten by animals and birds. If the food is suitable for commonly found animals, then it is not considered Muktze, even if one does not possess said animals. If the animals are not common, then such food is not considered Muktze provided that one possesses that type of animal.
Regarding the parameters of “commonly found” animals, Rabbi Ben Zion Abba Shaul (Or LeZion, vol. II, ch. 26, pg. 216) writes that if dogs, for example, are common in one side of a city and not on the other, then foodstuffs suitable to dogs would be considered Muktze in the latter side of the city. Rabbi Ovadia Yosef (Yabia Omer, vol. 9, O.H. 108, note 154) takes issue with this position and writes that as long as there are dogs in the city, then such food is not considered Muktze, even if no dogs are in the vicinity to actually consume that food. According to Rav Ovadia, the common presence of a certain animal in a locale imparts the status of “food” on items that are suitable to be eaten, and therefore they are not considered Muktze. Rabbi Shlomo Zalman Auerbach (Shemirat Shabbat Kehilchata, ch. 12, note 91) says that even if there are no dogs in one’s town, anything that may be considered dog food is enough to not be considered Muktze.
Another practical implication of this Halacha involves pits, nut shells, and the like. Since these are not fir even for consumption by animals, they do not have the status of food and are considered Muktze Mahmat Gufo. Regarding egg shells, the Ben Ish Hai (Parashat Miketz, 15), Rabbi Avraham Alkalai (Zechor LeAvraham, vol. III, pg.48) and Rabbi Avraham HaKohen (Me’at Mayim, 22) all write that they are not suitable for animals and are thus considered Muktze. Therefore, when peeling eggs in the Dafina, for example, one should be careful to discard the shell once it is off the egg.
Summary: Any food which is suitable for animal consumption has the status of food and can be handled on Shabbat. Shells, pits and the like are considered Muktze.