Unstable goo in general.
2 issues with it.
First issue is that it deletes what's in your hand to make room for the goo, let's say a head that you're about to re-attach, gone forever, taking that poor sod out of the round for good.
Second issue is that it keeps being reproduced even if the body has been cured.
Not entirely sure if either of these are features or bugs, but oh god why.