Baltic amber stone with fossil inclusions- 3 small-headed flies, Acroceridae.
The Acroceridae are a small family of odd-looking flies. They have a hump-backed appearance with a strikingly small head, generally with a long proboscis for accessing nectar. They are rare and not widely known. The most frequently applied common names are small-headed flies or hunch-back flies. Many are bee or wasp mimics. Because they are parasitoids of spiders, they also are sometimes known as spider flies
It weighs 0.6 grams. Measurements of stone 16x16x3.4mm, length of each fly ~ 2.7mm.