I have always wondered how Acrostichum establishes in aquatic or semi-aquatic habitats. In the mangrove forest of the Sungei Buloh nature reserve in Singapore, I observed that the gametophytes of Acrostichum speciosum were establishing on soil mounds produced by mud crabs. The mounds rise above the level of high tide. I did not observe any gametophytes or sporophytes that were not on these mounds.