Thallid

Thallids are fungus creatures created by infused with green mana, specific to the Magic: The Gathering Multiverse. All Thallids have the Fungus subtype.

Description
Used as cattle, thallids produce saprolings which are used as a food source and contain high amounts of green mana. Thallids were featured specifically in the Fallen Empires expansion, and later the Time Spiral block. Future Sight seemed to indicate that a thallid variant called Sporoloths would appear in the future somewhere.

Sarpadian Thallids
In the wake of the Sylex Blast, the empires of Sarpadia were left in a lurch as food sources began to dwindle. The elves, whose crops were failing, began to rely on eating fungus that grew rampant in the wake of increased decaying matter. Thelon, an elven druid, using methods borrowed from the Order of the Ebon Hand infused the fungus with green mana to create a living creature that produced saprolings. The fungus thrived in the forest, drawing mana that rivaled the elves' abilities.

Farmed as if cattle, the thallids would eventually gain sentience and begin to develop rudimentary signs of intelligence such as wielding weapons and creating shelter. The elves would be split into two factions over outright destroying the thallids or assisting them and finding new food sources. The elves, weakened by the political rift, would eventually be overrun by their own creations. This is partially due to difficult combat against the thallids whose fungus roots made them near impossible to kill. By their own nature there were often more thallids after battles than before.

Thallids would assist the orcs, goblins and thrulls in destroying Icatia, and would be one of the only sentient races on Sarpadia to not be exterminated by the thrulls. Thallids continued to evolve into new varieties, but never seemed to become much more than shambling brutes. Unlike thrulls, thallids were never known to show true intelligence, instead merely copying what they saw others do. It is not known why the thrulls and thallids are able to co-exist, but with similar origins and natures they may recognize the vast similarities between them.

Sporoloths
Sporoloths appeared on Dominaria from the future during the Time Spiral crisis. Appearing to be towering fungus creatures, little is known about them besides them exhibiting features very similar to thallids.

Slimefoot
Slimefoot is a Thallid which grew out of a small spore attached on the hull of the reconstructed skyship Weatherlight. As such it became an unofficial member of Captain Jhoira's crew.

Alaran Thallids
On Alara, thallids similar to those found on Dominaria dwelt in the Jund shard. They also share some affinity with saprolings, like their Dominarian relatives. As Jund exists in a primal state of struggle, the thallids must strive to avoid ending up as a delicious morsel for predators.