Unidentified hitchhikers

[graham stiles]

I just received a shipment of live rock. Had two hitchhikers that I can't identify. They can be seen in the attached pictures. Out of the water they would ball up, but had no armor and were about 2 inches long. Were dense and once in the water would stretch out like a slug to about 4 inches long and had two feelers that came out. What is this and is it a friend or foe of my reef tank

 

[Janice12]

It's a chiton of some sort, maybe someone else can narrow it down to a species. Generally good guys.

 

[Bongo Shrimp]

Thanks Janice12, I'll take it from here-

It's defenitly a chiton, Cryptoplax larvaeformis to be exact (or at least pretty close).
It's a harmless herbivore, part of the CUC.

 

[graham stiles]

Cryptoplax larvaeformis is exactly what it is. See the link to a deep sea photograph of one. http://www.deepseaimages.com/dsilibrary/showphoto.php?photo=18558
Good job!