Bellia - The Well Monster

In my country, Malta, we have this folklore creature called the Bellia. It lives in a well and was said to abduct children that go close to wells.

There is no actual depiction of this creature so I always believed it was some kind of water lizard or a huge worm.

My Idea for this creature is the following:

If you throw diamonds in a desert well the monster has a chance of throwing a valuable item.

If you throw anything else the creature extends its tongue and takes you to its dimension. This dimension is a small bedrock area that starts a boss fight with it

The monster will attack:

1. With acid that it shoots on the ground.

2. it grabs you with its tongue and bites you. You can free yourself by doing enough damage to the tongue while being pulled in. If you're blocking during this attack, the shield drops and is eaten by the monster but you remain safe. There is a chance the shield will drop after you kill it. Using multiple shields will only drop one shield at the end of the fight. 

This Monster can only be hurt with the following enchantments. Impaling, Piercing, Power, Sharpness, Smite, Bane of Arthropods, and Thorns. Unenchanted weapons won't deal damage unless he grabs you with the second attack.

It drops some valuables and its hide, that can be used to upgrade the damage reduction of a shield. If you die and go for revenge, it might drop some of the items from your previous battle.

I mostly wanted to give the Idea for a mob that lives in the well.