This might not be a proper bug, but the following items borrow a map icon from another object despite looking completely different.
Town House uses the Pig House map icon, Tall Grass uses the Grass map icon, Obsidian Fire Pit uses the Fire Pit icon, Sea Trap uses the Trap icon and Basalt Eruption uses the Boulder map icon.
Steps to Reproduce
Spawn/Find Item, Check Map.
This issue has not been confirmed by a developer yet.