Rewrite each original sentence in order to make it easier to understand by non-native speakers of English. You can do so by replacing complex words with simpler synonyms (i.e. paraphrasing), deleting unimportant information (i.e. compression), and/or splitting a long complex sentence into several simpler ones. The final simplified sentences need to be grammatical, fluent, and retain the main ideas of their original counterparts without altering their meanings.

Example input: From its inception, it was designated a duty-free port and vied with the neighboring Sultanate of Pattani for trade.
Example output: From the start, it was chosen to be a duty-free port to compete with the neighboring Sultanate of Pattani for trade.
Example explanation: In this example complex words are substituted with simpler ones. The word 'start' has taken the place of 'inception' and the verb 'compete' is used instead of 'vie'.
Q: The color has been speculated to be due to organic compounds on its surface.
A:
The color might be due to organic compounds on its surface.