This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
鉆 combines 金 (metal) with 占, which likely contributes a phonetic element. The exact historical development is uncertain.
The left side is metal 金, and the right side is 占 (occupy/divine). Without a clear meaning, picture a mysterious metal tool used in ancient divination.
For テン, imagine ten metal divination tools laid out: ten -> テン, and each one is made of 金.