Question mark
In the early 13th century, when the growth of communities of scholars (universities) in Paris and other major cities led to an expansion and streamlining of the book-production trade, punctuation was rationalized by assigning Alcuin's stroke-over-dot specifically to interrogatives; by this time the stroke was more sharply curved and can easily be recognized as the modern question mark.
Asterisk
The asterisk derives from the two thousand year old character used by Aristarchus of Samothrace called the asteriskos, ※, which he used when proofreading Homeric poetry to mark lines that were duplicated. Origen is known to have also used the asteriskos to mark missing Hebrew lines from his Hexapla. The asterisk evolved in shape over time, but its meaning as a symbol used to correct defects remained.