Cattails are naturally occurring bulrush-like plants consisting of dark green reeds-like thin leaves half a block in height and two tall stalks with two beige-brown piston-like longish spikes on top one block in height that can only be found in Swamplands - mainly on Bog Water, but also sometimes on blocks of green Grass close to the Bog.
These non-solid non-flammable plants are not able to regrow nor to spawn in time after world creation.
Different to most Flowers, Cattails do not have a cubic shape, but can still be placed on every type of ground or blocks just like they are. However, Cattails are not solid, so player characters and Creatures can pass through them.
No crafting recipe is known that will make use of Cattails, and they cannot be burned as a Fuel for Forges. These non-flammable plants can merely be used for decoration.
How to obtain
Cattails can only be found in Swamplands - mainly "swimming" on shallow green Bog Water, but also sometimes on blocks of green Grass close to bodies of Bog Water, usually amongst a much larger number of Reeds.
These plants are part of any newly created Creativerse game world, since they are fixed elements of the prefabricated template worlds that every newly created Creativerse is a copy of. To collect these plants, no Power Cell is required and no Mining Cell will lose durability when harvesting Cattails, except for outdated Wood Mining Cells.
When picking up a block of Grass or a unit of Bog Water with a patch of Cattails on top (no matter if naturally occuring there or having been placed), the Cattails will automatically be added as an additional harvest, just like Red Mushrooms, Tallgrass, Savannah Tallgrass, Weeds, Reeds and the like.
Cattails do not grow (they do not spawn in time by themselves) after world creation, nor will they regrow after being plucked; they also cannot be grown nor "crafted" by players. It does not seem possible to multiply Cattails by placing them on the ground and picking them up again either.
Such, Cattails are finite resources, but since they can be placed, they can optionally be infinitely bought as part of building kits for Blueprints.
Please note that even though Cattails are non-flammable, patches of Tallgrass are flammable awfully well - these grass stalks can often be found on blocks of green Grass in Swamplands next to Bog Water and occasionally close to Cattails and Reeds.
How to use
No crafting recipes are known that would make use of Cattails; they cannot be used as a Fuel for Forges and cannot be processed into pigment, slopes or anything else. These uncommon swamp plants also do not glow in the dark at all.
Cattails can be placed into the game world for decoration, however these plants are not solid (no collision mesh), so the movement of player characters and Creatures will not be obstructed; they cannot stand on Cattails either, but will pass through them like through thin air.
Please note that just like Tallgrass, Savannah Tallgrass, Red Mushrooms, Cattails, Reeds, Weeds, Lilypads, thin layers of Snow and the like, Cattails can be replaced and such deleted if blocks or items are placed directly at and such into them.
When placing Cattails, they can either be positioned in the centre of one block or at one border or even in one corner, and the Cattails then even look a little different too depending on their position. When rotating these bulrush plants to their side, they can either stick to a wall block with their base "correctly", or might be stuck in the block nearly halfway, or can "levitate" without even touching the wall block at their base.
Even though Cattails are not cubic blocks, they can be fully rotated into all directions by pointing your cursor at them, then pressing and holding R (as the default key) and then moving the mouse while holding down the left mouse button. The chosen rotation angle can be "locked" too by simply typing "r" while looking at an already rotated plant, block or item, so that all plants of the same stack in the chosen quickslot will then face the same direction when being placed.
Cattails are not known to make any type of Creatures spawn.
These plants can be put on display in display containers like Placemats, Stone Wall Shelves, Hidden Temple Altars, Galactic Grav-Chambers, Frozen Containers, Holiday Decorative Trees, Snow Buried Containers, Wood Planters, Flower Pots or the like, where they will be displayed in a smaller size. Anything that is placed into slots of display containers cannot be rotated.
Another option would be to simply place Cattails onto the pots in the game world instead of into their slots which will let the plants keep their size; however you will then be able to see the plants hovering above Flower Pots a little, since these pots are lower than one block. Also, because of their somehow random positioning, they might even look like they would levitate over the edge of a pot, not at all within its bordering.