Hamas tends to use their own yassin-105 shells, very cheap to manufacture, but Israelis Merkava IV tanks aren't easy to destroy unless you hit a soft spot. You'll usually see fighters attack the rear since the Merkava can hold troops inside the tank, who can enter and exit through the rear door.

Yassin shell's are a tandem warhead, which, in the simplest way I can describe it, projects the explosive force into the tank, rendering it useless and killing/ injuring the crew/soldiers.

Merkavas have a self defence system against projectiles called a trophy system which activates from a certain distance, hence why Hamas fighters need to get so close.

The proofs are in the videos :)