Complex sentence: Although radiocarbon dating of freshwater mollusk remains indicated an age of about 7,500 years, one should note that radiocarbon dating in freshwater mollusks in particular can be inaccurate.
Split into simpler sentences: Although radiocarbon dating of freshwater mollusk remains indicated an age of about 7,500 years. One should note that radiocarbon dating in freshwater mollusks in particular can be inaccurate.