The brown buble with 2 holes I think the hermit crabs keep kicking it around its no longer where I placed it is behind the mushroom rock

if it is a sponge how many watts/g do I need to keep it happy?
My last test results were:
PH 8.0
KH 7dh
Amonia 0
NO2 0.3
SQ 1.024
Temp 80F
Are those okay for the Brittle Stars??