Consider the evidence...
Just curious---for you guys with tank experience, Is that damage survivable for the crew? Or does the concussion from the HE explosion go through the crack(s) and kills the crew?
I couldn't say, having never survived such hits on my turret.
The damage does not look like it was done by HE rounds--it looks like more than one hit by
"shot" rounds, ie the garden variety Allied AP round, which was essentially a pointy cannonball (sometimes with a hardened core). I don't think that a soft-nose 75mm HE round would even make a dent in that armour, especially at that oblique angle of incidence.
It looks like the turret was hit by at least two AP rounds fired in quick succession that ricocheted off. I looks like the shock of the multiple hits caused the armour to crack.
Also, check the angle of elevation the shots struck--if they were fired from in front of the tank (most likely) then they appear to have come in from below the level of the turret (unusual).
If, however, they came from the direction of the tank's rear, then the evidence suggests they came in at a downward angle in the manner of close-range artillery shells--yet having two or more howitzer shells landing so close together is a near impossibility. Otherwise, the rounds might well have been those same AT/'shot' rounds I mentioned earlier.
Their trajectory is commensurate with shot fired from about 800 yards astern.
These are not the 75mm tank shells typical of the M-4 Sherman, but they are the ones for the M-10 tank destroyer and the long-barreled 76mm Sherman. The one on the bottom is the "shot"/anti-tank/armour-piercing round, and the one in the middle is an HE round.
HE will damage equipment such as lights or fenders, but will not penetrate tank armour.
How about rockets launched from a ground attack fighter-bomber, e.g. Thunderbolt or Typhoon?