The lump on the 5 is caused by a die chip, (US term) basically the die developed a break or hole where there shouldn't be one, and the result is this lump. I've never seen this error before.
Another possibility is that it's a bit of silver solder applied by someone in the coins past.
The missing denticles may be due to wear, or the coin may have been minted slightly off centre, but I think it's too worn to be able to tell for sure.
It also appears to have been cleaned fairly harshly at some time. It may have been a detector find.
Value is probably only silver melt give or take a dollar or two.
life is a mystery to be lived not a problem to be solved