Abysium Eater

Fallout Susceptibility (Ex) A creature hit by an abysium eater’s slam attack takes a –1 penalty to its next saving throw against radiation sickness attempted within the next 24 hours. This penalty stacks, to a maximum equal to half the abysium eater’s CR (–2 for a typical specimen).
Irradiation (Ex) An abysium eater emanates medium radiation in a 20-foot radius. This radiation suffuses an area in 20-foot increments. An abysium eater is considered a natural radioactive material for the purposes of spells that remove radiation, such as remove radioactivity.
Shear Shielding (Ex) When an abysium eater critically hits a creature wearing armor that grants immunity to radiation levels, the target loses that radiation immunity (Reflex DC 13 negates), though the armor continues to provide its saving throw bonus against radiation as normal. This damage persists until the armor is repaired.

Strange protoplasmic pests that subsist on the rarest of metals, starmetal eaters usually remain microscopic and innocuous. Yet when these creatures gorge themselves on a rich vein of naturally occurring starmetal or even items made of starmetal alloy—either of which they can detect at great distances—they experience a swift growth spurt and can reach several feet in diameter. Each starmetal eater fixates its diet on one specific type of starmetal, gaining strange abilities as its appearance and essence are suffused with its metal of choice.