This is a rare piece. First there is a twig (or the remains of a twig) going through the amber. But much more importantly, there is a Bristletail, Apterygota, Zygentoma. These are wingless true insects. This particular one is fairly good sized. A superb example of a Bristletail in Baltic amber.
Mayfly - Order Ephemeroptera. Mayfly eggs are laid in water and are hatched within one to two weeks. The nymphs develop for a year or more in water. When they emerge into the air, their life span is counted in hours. Mayflies are very rare in amber. This particular mayfly is in a nice piece of amber, but it is difficult to see. Many microscopic air bubbles impede clear visualization of the animal. Needless to say, this is not a 'cleared' piece of Baltic amber.
About 2/3 of an inch in size (amber) and the stonefly is about a 1/2 inch. Bottom line, this piece of amber has the rare and massively sought after stonefly, Plecoptera. While fully developed larvae are occasionally found in amber, the exuviae (molt) and particularly the winged imagoes are most common. This is not the molt, but the actual animal. The mature larvae leave the water and often climb up nearby tree trunks to shed their last exuvia and become winged imagoes. As stoneflies develop only a low affinity for flying and usually walk rather than fly in the event of danger, in search of food or to mate, their dispersal in minimal and often limited to the immediate vicinity of their original aquatic habitat.
This is certainly a different piece. There is quite a story to weave around this piece. Going through the resin is what I feel to be a stick. Attached to this stick was a ant colony. The resin must have dripped on to the colony of ants some 45 million years ago. Mostly there were female worker ants, Hymenoptera, Formicidae, scurrying around. Part of the hive that housed juveniles was also here. There is a pupa that died immediately prior to hatching. This is the first time I have ever seen that. Must be two dozen worker ants who lost their life in the sap. Part is very clear, part has a rough surface. An amazing piece of amber.