Took my engine apart. Is this a Crack?

[GvEman]

I started a couple of weeks ago with ripping the old tiered engine out of the car and I started to pick it apart. Yester day I took the pistons out of the block and I found out it was about time. The timing chain for example was so slack so you could almost pull it of the wheels!! Is that good?
And when I lifted the crank out I found this.



Looks like some kind of casting fault but I don’t know if its critical.
I did also notice that the bearings was quite worn out.. The crank bearing in front of the engine was quite good but as I got further back they got worse and worse. Bad crank?

Just some pictures of the other parts...








So what do you say? Do i need to buy another block or another engine?

Cheers