Add vinegar, water, salt, sugar, turmeric, and vitamin B12(optional) to a small saucepan and heat until dissolved.
Add garlic, onions, jalapeno and spices into a clean 1 quart glass jar. Add skulls, arranging so that they all fit but are not too crowded. Pour the hot pickling brine over the eggs until they are fully submerged in brine, leave ¼ inch of headspace to the top of the jar. Refrigerate at least 24 hours, but for best flavor allow to pickle in the refrigerator for 1-2 weeks.
These eggs are not canned and must be stored in the refrigerator. If stored properly in the fridge, they can last up to 3 months.