1 of 8: Koola, an 18-year-old western lowland gorilla at Brookfield Zoo, enjoys a heart-shaped treat for Valentines Day. The nutritious cookies are made of ground primate biscuit, oatmeal, bananas, raisins, and peanut butter. The Animal Programs staff for the Chicago Zoological Society is always thinking of ways to physically and mentally stimulate the animals at Brookfield Zoo. One way is by providing them with a variety of different enrichment and food items they normally do not receive on a regular basis. (Photo/Jim Schulz/Chicago Zoological Society)

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