Double ID please

[AMOON32]

These two critters just appeared after several months of nothing new. Tank has been up and running for about 5 months at this point. Any ideas what they are and if they are reef safe?
Thanks — Andy

 

[lewisriverfisherman]

Rock urchin and a limpet would be my best guess

 

[reef lover]

Keyhole limpet some like to dine on sps...i had one eat a whole stylo frag in one night....

 

[AMOON32]

Thank you for the responses. I found that I have at least one more limpet, but they all seem to minding their own business right now. I will keep an eye on them to be sure. I hope I don’t have to remove them, they’re pretty cool to have in there.