I found the rock on the beach. It has a redish hue and floats on water. It feels as though it is hollow because it is light for its size. Does anyone have an idea what this is?
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$\begingroup$ you sure its not plastic? $\endgroup$ – John Aug 5 '18 at 14:47
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1$\begingroup$ Rocks usually do not float on water. The only rocks that float on water are very porous rocks like pumice. $\endgroup$ – Gimelist Aug 6 '18 at 10:30
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This isn't a rock at all, but a seed of Entada Gigas, sometimes called the sea heart or sea bean.
(Entada Gigas is called the "sea bean" for good reason: it's a member of the bean family Fabaceae. In fact, this species has the family's largest seed, a flattened heart shape 6 cm in diameter and 2 cm thick. These hollow seeds are washed into the ocean and drift on currents for up to 2 years, on the chance that one will wash up somewhere to germinate. It seems that sea beans have evolved to propagate in this way, similar to coconuts.
