That is a kelp-like calurpa. I baught some before, it grew like a weed, like all calurpas. However This suff "bleeds" white stringy goo if you cut it. TRY IT. Im not sure what the goo is or if it is bad or not. But I prefere to use grape calurpa. But this stuff makes a nice hiding spot for critters in a sump or fuge, or even in a spot in the main tank. Perhaps in front of a cave...
