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What I'm looking at right now
are these really bulbus pillow flows.

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They're really rich in volcanic
glass. That lava that's been

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erupted on the seafloor has
quenched and cooled really

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quickly and that's preserved
this glassy state of that lava

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that we use for subsequent
geochemical analysis. The crust

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itself is about over 90% silicate
minerals. While most of the

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ocean's silica input comes from
rivers, about 20% comes from

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weathering of the seafloor
including pillow basalts like

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these. And so what's always
interesting to me is these

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biological organisms that also
have silica-based skeletons and

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how they depend on the silica
that's in the water column that

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might be derived ultimately
from volcanic products to build

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their skeletons. It's
interesting that you say that, we just

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passed over two glass sponges,
the Hexactinellida, the glass sponges. the

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glass in the name refers to all
the silica that they've

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incorporated into their
skeleton and one of the cool

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things is to think about how
all of these elements of the

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Earth are interconnected
because to get the silica to

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deposit in the skeleton, they
have to take it out of the water and

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where is it coming from the
water? It's probably dissolved

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or has been released from the
interior of the Earth or the

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weathering of the rocks that
you were just talking about. In

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one study that's been
published, it's been shown that

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sponges can take up
approximately 36% of the silica

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that's dissolved in seawater.
It's a one big cycle.