no, you wouldnt because even the most cruel poisonous monsters have their enemies too.
i remember we used to collect crown of thorns (your 1st pic) after their invasion in 1999... they appeared out of the blue and like a raging epidemic, they swept off the entire coral population of huge coral reef systems. after carefully removing them from coral blocks (with gloves and knives, and in one piece, as just a single torn off arm could have survived and developed into a new seastar) we brought them to an island where tons of them were burned. dangerous beauty... found it always fascinating why nature has made these devastating creatures so pretty. very good underwater pictures... the backscatters (not again;) appear like an underwater star canape.