I have two suggestions:

• Icicles that point upwards. Similar to how dripstone can face upwards vertically, why not icicles? They'd be great for making traps and such!
• Archaeology in the Lost Caves. Given the name of the cave biome and the environment of it, it's a perfect biome to include archaeology, including suspicious sand, unique structures, and special artifacts exclusive to the mod.

I hope you can consider these!