At the end of Exodus we just read of תחש TahK[H]ahSH skins in the Tabernacle.
What are these? The attempts to identify them are weird. The ArtScroll Bible leaves it untranslated.
Translators unaware of seals in the Persian Gulf, whose waterproof skins were sold along the desert trading route, have rendered the term "dolphin" or "badger" (KJV). Goods from China to Egypt were traded along the Silk Road. Badgers are small and don't congregate in large colonies; it is hard to imagine finding enough badger skins in the Middle East to cover the Tabernacle. Sealskin is long-established commercially as a waterproofing.
Lamer than dolphin skin, Brown-Driver-Briggs cites "dugong" and "sheep skins" as theories for the meaning of תחש (S)ahK[H]ahSH.
SEECATCH is a little-known word for a large fur seal. This adult male of the Alaska fur seal is from Russian sekach. This provides a good new possibility of identifying the תחש TahK[H]ahSH or (S)ahK[H]ahSH of Exodus 25:5 and elsewhere.
The pronunciation of (S)ahK[H]ahSH is not yet accepted by the expert Hebraists who have no clue that massive data shows Hebrew to be global and more versatile in pronunciation than they thought. As in the next post, also about a Tabernacle material, Hebrew students have to learn that what they were taught is an Askenazik or Sephardic accent (of Hebrew speakers from Europe or the Near East) is really a global variant, both equally valid.