The most common and most likely answer to this crossword clue is the 11 letter word OBSCURITIES
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More clues leading to the result OBSCURITIES
Buddy explains!

The straight part
We know that "Little is known about these" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case little is known about these = obscurities.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does OBSCURITIES mean?
OBSCURITIES noun- Darkness; the absence of light.
- The state of being unknown; a thing that is unknown.
- The quality of being difficult to understand; a thing that is difficult to understand.