Since Creativerse is a 3D block-based game, all game worlds mainly (but not solely) consist of cubic natural blocks.
Other than that, several non-cubic plants like Shrubs, Tundra Flowers, Savannah Wildflowers, Tallgrass, Savannah Tallgrass, Weeds, Reeds, Cattails, Lilypads and of course Red Mushrooms can be found in different biomes on the surface worlds of Creativerse. Snow often comes in the shape of thin layers (eighths) in Tundras and Canyons.
Players can craft other placeable shapes than cubic blocks themselves, like slabs, slopes, stairs, columns, rounded slopes and corner blocks for both common slanted slopes and stairs. Moreover, a nice assortment of furniture and other placeable objects can be crafted as well.
Since update R22 on September 16th 2015, the only non-cubic "objects" that you can find on game worlds just by exploring are randomly spawning Treasure Chests and their seasonal sisters, the randomly spawning Holiday Gifts (that will only appear on cold-emitting blocks of Snow and Ice during Christmas Holiday). Before that, Crafting Stations randomly spawned on old Early Access game worlds as well.
Also, Creatures are not cube-based, neither are their Loot Bags. In Creativerse, Creatures do not "drop" eggs or any other resources in the shape of 3D items. Instead, only if they die, all of their drops are neatly collected in Loot Bags respectively Ghost Loot bags. Stuff that you harvest from your Pets directly goes into your inventory/bag though.
Nearly all natural blocks that can be collected/mined, can also be placed. Ore Nodes cannot be removed nor destroyed, instead the Ore inside them can be extracted by using Extractors of different tiers. After all Ore has been extracted, the Extractor can be removed by being emptied, and the Node will vanish together with it.
Also all types of Liquids can be scooped up in Creativerse and then placed into the game world. When they extend, some of their extensions are thinner than a full cubic block would be.