Clockwork Caterpillar

Mechanical. The caterpillar is a construct and doesn’t require air, food, drink, or sleep.

Consumption. Over a long rest you can have the Caterpillar consume one basic non magical item, be it a stick of wood, a chain tunic, a short sword, or anything. 

Chrysalis. After each successful counterspell you must note what spell was consumed. After it is able to successfully consume 5 spells, it then begins its chrysalis stage. it remains in this state for 3 days, where it merges with the non magical item.Then when the chrysalis hatches it leaves behind a new magical item based on what spells it was able to consume.

Bite. Melee Weapon Attack: +4 to hit, reach 5 ft., one creature. Hit: 1d6 piercing damage.

Absorbtion. The Caterpillar knows and can cast Counterspell once per long rest, instead of hand-waving a spell away, the caterpillar actually attempts to eat the magical effect. The spell is stored by the Caterpillar inside one of its body segments. The spell can not be recast by the Caterpillar.

Barbed Skin. When a creature within 5 feet of the caterpillar hits it with a melee attack or starts their turn while grappled by it or grappling it, it can use your reaction to deal 1d6 piercing damage to them.