Question: Micropalaeosoma balticus is an extinct, fossil turbellarian flatworm known from Baltic amber from an exclave between what two countries? 

Context paragraphs:
Elephantomyia baltica: Elephantomyia (Elephantomyia) baltica is an extinct species of crane fly in the family Limoniidae.  The species is solely known from the Middle Eocene Baltic amber deposits in the Baltic Sea region of Europe.  The species is one of six described from Baltic amber.

Micropalaeosoma: Micropalaeosoma balticus (formerly "Palaeosoma balticus" ) is an extinct, fossil turbellarian flatworm known from Baltic amber of Kaliningrad, Russia, that lived approximately 40 million years ago.  It measured approximately 1.5 mm in length and is the oldest and most complete flatworm fossil yet discovered.

Kaliningrad: Kaliningrad (Russian: Калининград ; ] ) (former German name: Königsberg; Russian: Кёнигсберг , "Kyonigsberg" ; Old Prussian: "Twangste, Kunnegsgarbs, Knigsberg "; Polish: "Królewiec" ; Lithuanian: "Karaliaučius" ) is the administrative center of Kaliningrad Oblast, a Russian exclave between Poland and Lithuania on the Baltic Sea.

Elephantomyia pulchella: Elephantomyia (Elephantomyia) pulchella is an extinct species of crane fly in the family Limoniidae.  The species is solely known from the Middle Eocene Baltic amber deposits in the Baltic Sea region of Europe.  The species is one of six described from Baltic amber.

Elephantomyia longirostris: Elephantomyia (Elephantomyia) longirostris is an extinct species of crane fly in the family Limoniidae.  The species is solely known from the Middle Eocene Baltic amber deposits in the Baltic Sea region of Europe.  The species is one of six described from Baltic amber.

Eopauropus: Eopauropus balticus is a prehistoric pauropod known from mid-Eocene Baltic amber.  It is the only known pauropod in the fossil record.  As pauropods are normally soil-dwelling, their presence in amber (fossilized tree sap) is unusual, and they are the rarest known animals in Baltic amber.

Elephantomyia brevipalpa: Elephantomyia (Elephantomyia) brevipalpa is an extinct species of crane fly in the family Limoniidae.  The species is solely known from the Middle Eocene Baltic amber deposits in the Baltic Sea region of Europe.  The species is one of six described from Baltic amber.

Elephantomyia bozenae: Elephantomyia (Elephantomyia) bozenae is an extinct species of crane fly in the family Limoniidae.  The species is solely known from the Middle Eocene Baltic amber deposits in the Baltic Sea region of Europe.  The species is one of six described from Baltic amber.

Notoscyphus balticus: Notoscyphus balticus is an extinct species of liverwort in the family Geocalycaceae.  The species is solely known from the Middle Eocene Baltic amber deposits in the Baltic Sea region of Europe.  The genus contains a total of thirteen extant species distributed across the northern hemisphere.

Elephantomyia irinae: Elephantomyia (Elephantomyia) irinae is an extinct species of crane fly in the family Limoniidae.  The species is solely known from the Middle Eocene Baltic amber deposits in the Baltic Sea region of Europe.  The species is one of six described from Baltic amber.

Supporting paragraphs: Micropalaeosoma Kaliningrad
Answer: Poland and Lithuania