Fast growing, to the point of being somewhat invasive... and WEAR GLOVES if you're going to handle them, but no... they're not a 'bad' thing. I've got a patch of mint green palys, they're good for covering areas where nothing much wants to grow
yes the paly i got it on rock from begining and it grew fast so i liked it so i spread it on some other rocks didnt know how bad they were to have should i be consernd dont know the id of them
i guess if mabe i made bad move i feel like i was helping it spread i didnt mind how it looks just not sure how poisionis it is as long as i dont kill it or scrub it off the rock and wash my hands when dealing with it should i be fine?
I think you'll find that the majority of mixed reef tanks end up with some palys. They're great ground cover in a reef Don't panic about it. As to how poisonous it is... enough that you want to avoid exposure, not enough to worry about having it in your home.