He was born in
Borge Municipality in the
Lofoten Islands of
Nordland, Norway. During his childhood, he developed an interest in natural history and in collecting plants and animals. Foslie worked in the Norwegian telegraph service from 1874 until 1885, first in the Lofoten Islands, then in Oslo. He was 29 in 1885 when he began his first full-time scientific position as a curator at the
Tromsø University Museum in
Tromsø. With a travel grant from the university, he studied in
Great Britain and
France. He later visited biological stations in the
Netherlands,
England and
Scotland. Foslie then moved to the
Museum operated by the
Royal Norwegian Society of Sciences and Letters at
Trondheim in 1892, where he remained until his death in 1909. Ín 1950
Olav Gjærevoll issued the
exsiccata M. Foslie: Lithothamnia selecta exsiccata distributing specimens collected by M. Foslie. Foslie contributed an algal collection named
Algae Norvegicae to the
Ulster Museum in
Belfast,
Northern Ireland. This collection was donated to the Ulster Museum by The
Queen's University of Belfast in 1968. The specimens have been catalogued into the main collection in the Ulster Museum catalogued: F10319 - F10336. It is assumed that this refers to Mikael Heggelund Foslie. The specimens bear dates from the 1880s to 1890s. Mikael Foslie was a member of the Science Society in Kristiania (now the
Norwegian Academy of Science and Letters) from 1891 and of the
Royal Norwegian Society of Sciences and Letters from 1892. ==Publications==