Need confirmation on star id

[cathbad]

Could this be Ophioderma brevispinum? If not any ideas as to what it may be are greatly appreciated. It came in on Gulf rock and over the past 18 months it has grown to 5-6 inches across. What can I expect as a final size?
Sorry for the quality of the pics. It seldom shows more than a little bit of arm looking for food.

 

[cathbad]

Another

 

[cathbad]

Last one

 

[ccamaleon]

serpent sand star good for u cleaning crew i do not if a coral safe:notsure:

 

[ophiura]

Actually looks more like an Ophionereis- perhaps Ophionereis reticulata if it has a nice pattern on the disk...but this not too meaningful. Probably not Ophioderma which would have smaller spines (from what I can see). Will have to remember to check my books tonight for total size. "Reef" safe, yes, though I put in a disclaimer that they will not pass up a meal. Generally a scavenger (which can now be spot fed)...but always a distant and probably very small risk to shrimp or things. Not known to be a predator, but I don't want to say never. Should be harmless....if you ever don't want it trade it in or I'll take it.

 

[cathbad]

Thanks for the information. I'm not too worried about its "reef safeness"; after 18 months it has bothered nothing. I am mainly interested in its adult size. I will continue to try to get a pic of the disc but this guy is very cryptic. I lured him out with shrimp in total darkness just to get this one. Again thanks for any information, including that already given.