Need help🫤....effing title too short 😡🤬😡

A few days ago I got given a whole bunch of fresh lemons off a friends tree.
I put them straight into my fruit bowl .

It's only been like 5...6 days - and they've gone mouldy !

The apples and the limes I have in there, (and were there first ), haven't .

So my questions are :
1. Do I have to wary be now of my other fruit doing the same ?
2. If so, how do I stop that ?
3. And why did the lemons get moldy in the first place ?

Anybody?🤷