Mana

Mana is similar to matter and antimatter. Rather than destroying its’ counterparts, mana sticks to them, changing how they behave. It cannot fuse or separate matter particles, but one mana particle can attach to multiple matter particles at once. Mana follows the normal laws of gravity, but the pull is not as powerful as it is for matter.
Most universes do not naturally contain mana, but in those that do, it is abundant. Our universe is an anomaly, in that it is linked to another universe; one made almost entirely of mana.
There are parts of our universe where the link is especially strong, and mana and matter can easily leak through. The mana in these areas often makes noticeable changes to the surrounding matter. A link at the bottom of a pond might create a “spring” of mana.
Living things that spend a lot of time in the presence of mana slowly mutate and often gain strange abilities. Mutations usually aren't noticeable in affected creatures, as their lifespans are too short, and their vitals are vulnerable to the slightest of changes, but offspring can be affected by mutation without harm. Common mutations for offspring include wildly discolored skin or hair, deformed limbs and facial features, bone protruding from the skin (horns, tusks, spikes etc.), and extra limbs or muscles. If left alone, mana buildup often causes birth to fail due to vital parts of the body developing incorrectly, but, this can be prevented by regularly monitoring mana levels and manually adjusting the mana attached to the growing baby so vital organs aren't interfered with.