Monsters that mimic objects and terrain

D&D has so many monsters whose shtick can be summarized as a simple formula:

1. Pick a taxonomic category like gastropod, cephalopod, manta ray, slime mold, etc.
2. Pick a piece of terrain, architecture, clothing, furniture, surface, etc
3. Create a monster out of category #1 that pretends to be object of category #2.
4. Voila!

This formula is so silly and overused that there have been numerous articles over the years mocking it. Such monsters are often called "obnoxious" or "stupid."

While some writers like to invent new ecologies for these trick monsters, I personally found it easier to treat them all as variations on the mimic. Eventually I might decide to explore ecologies for mimic snails, mimic squids, mimic rays, etc. But it seems a bit silly, no?