Sorry for the delay in getting to this.
There are three possible causes for this.
One is acclimation shock, but this also typically leads to arm loss...and typically arm loss is the first step. Animals can recover from this but tend to show behaviors related to this stress (staying in the open, etc).
The second is a feeding injury in which the animal quite literally eats something that is too big or too sharp and this pokes through the disk. Odds of recovery are generally quite good.
A third possibility is a predatory attack, but not by the worms. This would be something bigger, a fish like a wrasse, puffer or trigger. But again, most will get the arms first, and a hole such as this is not, IMO, a predatory attack.
Basically, if the animal has not lost arms, is in hiding, and is interested in food, I have every confidence that it will recover from this.
If it starts losing arms, staying out in the open, etc, then that is a bad sign.
FWIW, brittlestars are amazingly resilient animals are rarely fall ill with any sort of bacterial or viral problem, due to an astonishing array of symbiotic bacteria that live on them (which are, BTW, being investigated for use by humans). This appears to explain why they can sustain incredible damage such as this, and recover in relatively short order.
I had this happen with a couple of individuals.
From ammonia and pH burns (left in bag at LFS):
Unknown:
Check out what has been dubbed "Distended disk syndrome" in the
Tabloids section of my website.
The best thing to do is to leave the brittlestar where it is (moving it to another tank will cause it more stress) and remove anything that is seen picking at it.
