What would be the ideal terrain for promoting the evolution of blade feet that sink into the ground?

So, in my last question, I asked "How could an animal run fast using blade-like feet that sink into spongy ground?"

The premise was that on my planet, forests grow not from soil but from spongy, living mats. The creatures here have feet like blades, that sink into the squishy ground. However, while I did eventually find a solution that would make a blade-footed animal superior to a normal-footed one in terms of speed, a lot of people were saying that traditional, spread-out feet that rest on top the ground would be superior to bladed feet in such an environment. What environment would suit blade feet instead?

Preferrably, the terrain must be:

• Biological
• In a state that the blades sink into it
• At least semi-regenerative (So the ground isn't permanently chopped up by footprints)

It could be:

1. Moss
2. Fungus
3. Soft sponge (As in Porifera)

Or something else like that. One idea I had was that the organism that constitutes the ground has a soft, spongy exterior about 2-3 feet deep, and below it, there's a hard core. The blades of the animals would cut through the sponge and touch the hard bit, preventing them from slicing through the ground like butter and having trouble pulling their legs back out again, as this horrendously rough drawing shows:

(Don't worry, I'm better at drawing in real life.)

The evolution of blade-like feet would also bring a host of other advantages and uses to the creatures. They could be used for slashing prey, spearing fish, sensing vibrations, climbing and marking territory on tree (Alien tree analogue, that is.) trunks.

So, could any of you explain why bladed feet would evolve?

posted over 6 years ago

SealBoi‭

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