The Hebrew term tachash of Exodus 25:5 is considered by some scholars to be a reference to blue processed skins. Other scholars dispute this and suggest instead that the term refers to either an ermine or an okape antelope or an okape or a giraffe or lastly a narwhal or dugong. The above term appears in a text which notes the various types of offerings that the congregation are to bring to the Tabernacle.
The dugong is a kosher, large and protected marine mammal.
Habitat: Indian Oceans, and the shores of Sinai.