Complete avoidance of animal products can sometimes feel well-nigh impossible for even the most conscientious consumer. For those on the vegan-vegetarian-discerning omnivore spectrum, there may still be products in your everyday life you’re unaware contain or whose production involved animal ingredients.

Since anyone can benefit from being more informed about what they’re consuming, in Veganissimo A to Z, Reuben Proctor and Lars Thomsen offer a comprehensive reference guide to identifying and avoiding ingredients of animal origin, including some things not commonly thought of as not vegan.

Here are five of those harder-to-pin-down products:

String Instruments

Catgut, gut strings from sheep, has been used in surgical sutures and as strings for musical instruments and tennis rackets. There are now synthetic alternatives widely available.

String instruments like the violin and cello still use horsehair in their bows, but there is such a thing as a vegan violin bow.

Foods Containing Natural Red Dyes

Starbucks came under fire in 2012 for using carmine, a red dye from crushed female cochineal scale insects, in products like the Strawberries & Cream Frappuccino and the Red Velvet Whoopie Pie. Starbucks has discontinued the practice, but cochineal extract continues to be used as food coloring and as a fabric and cosmetics dye.

Carmine is labeled as Natural Red 4 and E120.

Movies

Any vegan worth their vegan salt substitute already has gelatin’s number. The gel-forming protein derived from animal skin and bone, especially cattle and pigs, is used as a binding agent and thickener in candies and cakes as well as meat products, but did you know gelatin can be found in the emulsion layer of photographs, films, and x-rays? Unless you’re seeing a movie in digital projection, your next trip to the theater may not be vegan.

Blood Clot Medication

Batroxobin, an enzyme from snake venom, is commonly used in blood work and for treating blood clot disorders.

Heparin, usually obtained from the intestinal mucous membrane of pigs, is a polysaccharide compound used routinely as a medicinal active agent for preventing and treating blood clots following severe injuries, after surgery or in the case of bedridden patients, either as subcutaneous injections or continual infusions.

Beer and Wine

Isinglass, fish glue derived from the air bladders of sturgeons and now other fishes, is used as a fining agent for wine, beer, and other beverages. Here’s a guide to what’s safe (and not) to drink.