Urchin ate small toadstool

[EricR]

My newish urchin ate a small toadstool overnight.
*pictures below

My primary questions are:
1. What type of urchin do you think this is?
2. Is this type of urchin known to eat leathers or other soft corals (or LPS) ?


Urchin purchased as “Halloween urchin” from online vendor, received 7/24/2026 (so 1 month ago).
Doesn’t look very “Halloweeny” but I assumed that was because it lost a lot of spines in shipping.

Tiny toadstool has a long back-story of neglect but was discovered (forgotten in back of tank) and remounted many months ago (early 2026).
Toadstool has been doing fine and growing (albeit maybe oddly-shaped) for many months.

Toadstool looked fine during the day.
Urchin was found on top of toadstool the next morning with most of the toadstool gone, down to a nub.


Here’s the urchin:

Here’s the only close-up I could find of the toadstool (from about 3 months ago):
*toadstool actually had more growth than this now but just to give some reference

Here’s the toadstool now:

I assume responses will be that toadstool was likely dying/decaying but, while not impossible, doesn’t fit with my recent visual observations.
If urchin is a coral eater, I might want to try to “direct” it to some zoa or Kenya tree overgrowth before I remove it.

 

[Mickle]

maybe it was seeking out extra nutrients for regrowing all the lost spines

 

[EricR]

maybe it was seeking out extra nutrients for regrowing all the lost spines

Nori and algae wafers just 'aint good enough for him!

 

[exnisstech]

Not sure what type it is. I've kept tuxedo and have 3 pin cushions that bother no coral even softies that are struggling. Mine try to move them to a better location lol

 

[Mickle]

Now that I have time I looked into it more. Looks like the species you have is 'Salmacis bicolor' which eats sea pens, soft bodied corals, and coral polyps as a secondary part of their diet

 

[EricR]

Now that I have time I looked into it more. Looks like the species you have is 'Salmacis bicolor' which eats sea pens, soft bodied corals, and coral polyps as a secondary part of their diet

Interesting. Will have to look into that more.
Thanks for the tip.

 

[EricR]

Now that I have time I looked into it more. Looks like the species you have is 'Salmacis bicolor' which eats sea pens, soft bodied corals, and coral polyps as a secondary part of their diet (

Yeah,,, I think you nailed it.
"Salmacis bicolor" and some, similar, Salmacis urchins seem to have same caution about soft-bodied corals potentially being on the menu, like you said.

Quick aside notes:
One night it was camped out in the middle of a pretty large GSP patch so I left it to see what would happen but the GSP looked fine the next day.

Last night I left it starting to climb up a Kenya tree but, again, didn't see any damage this morning. (Urchin may have given up before getting high enough to get to polyps but who knows).

Anyway, thanks again.