I watched a few different videos from the scene to try to figure out what they are standing in front of. The audio is messed up on all the different video angles and it's raining. Fox News and Dailymail say that the object is a baby crib.

https://youtu.be/J-Dt2hJ5TBs?t=30
https://youtu.be/H7EYyiIwlxQ?t=29
https://youtu.be/wwN9C6y4Y4g?t=26

I found a transcript here : https://news.yahoo.com/elon-musk-tours-attacked-kibbutz-123203470.html

The bald IDF guy on the left while describing what they are looking at, says "It's a symbol in kibbutz. We have kids inside. The mothers and the fathers went around this way. But it's holding shells-- specifically of a Negev-- that was used here in order to protect the people." Negev is an IDF machine gun.

For weeks now the IDF has been showing us manufactured videos of military equipment placed inside the bedrooms of children in Gaza. Making claims that this is evidence that Hamas is putting children in danger.

Today we have a video of the IDF displaying the crib of an Israeli child and inside the crib is Israeli bullet shells from an Israeli weapon. The IDF tells us that this is a symbol of mothers and fathers protecting their children. This is new levels of IDF propaganda.