I have thought many times during the last five years about what the sign looking like a shark-fin might be a picture of. Could it be the brilliant reflex of light on a mirror-like surface? Could it be a leaf indicating the life flourishing after fresh water has been given? As light and life are fundamentally the same phenomenon (vai-ora-a-Tane), it is difficult to judge. However, looking elsewhere for this sign I noticed that in ancient Sumer they meant it to show a hand. I thought that strange because there was no close similarity between a hand and this sign. However, now I have changed my mind (picture from Wilkinson):

The hands (and feet) of this Egyptian scarab looks like two-pronged claws where each such claw is quite similar to the 'shark-fin' sign. Only four of the six legs are here clearly seen. I believe the scarab is equivalent in meaning to the canoe-glyph with four 'fins' and that they both illustrate the rising sun. Claws, fins, or hands - same thing.