There are many additives that are hard to tell what they're from. Gelling Agents - these are called gelatine and aspic. They cannot be eaten by vegetarians but there are veggie alternatives. Isinglass - this is a very pure form of gelatine which is obtained from the air bladders of freshwater fish. Lanolin - this is contained in some cosmetics.
Most vegetarians avoid it.
It's made from sheep's wool and is usually a slaughterhouse by-product. Tallow - this is hard animal fat and should be avoided. Whey - this is residue from milk after the removal of the casein and most of the fat. It is often found in biscuits, bread, cakes and sweets. Vegetarians should avoid it because it was probably made with animal rennet.